Class Client (2.18.0)

The Google Cloud Storage (GCS) Client.

This is the main class to interact with GCS. It provides member functions to invoke all the APIs in the service.

Performance

Creating an object of this type is a relatively low-cost operation. Connections to the service are created on demand. Copy-assignment and copy-construction are also relatively low-cost operations, they should be comparable to copying a few shared pointers. The first request (or any request that requires a new connection) incurs the cost of creating the connection and authenticating with the service. Note that the library may need to perform other bookkeeping operations that may impact performance. For example, access tokens need to be refreshed from time to time, and this may impact the performance of some operations.

Connection Pool

By default this class uses HTTPS to communicate with the service. Creating a new HTTPS session is relatively expensive, as it must go through the TCP/IP and SSL handshakes. To minimize this overhead the class maintains a connection pool to the service. After each request completes the connection is returned to the pool, and reused in future requests. Note that for downloads (implemented by the ReadObject() member function) the connection remains in use until the download completes. Therefore, having multiple downloads open at the same time requires multiple connections. The application can limit the maximum size of this connection pool using storage::ConnectionPoolSizeOption. If returning a connection to the pool would make the pool larger than this limit then the oldest connection in the pool is closed (recall that all connections in the pool are inactive). Note that this is the maximum size of the pool, the client library does not create connections until needed.

Note that the application may (at times) use more connections than the maximum size of the pool. For example if N downloads are in progress the library may need N connections, even if the pool size is smaller.

Two clients that compare equal share the same connection pool. Two clients created with the default constructor or with the constructor from a google::cloud::Options are never equal and do not share connection pools. Clients created via copy (or move) construction compare equal and share the connection pool.

Thread-safety

Instances of this class created via copy-construction or copy-assignment share the underlying pool of connections. Access to these copies via multiple threads is guaranteed to work. Two threads operating on the same instance of this class is not guaranteed to work.

Credentials

The default approach for creating a Client uses Google Application Default Credentials (ADCs). Note that a default-constructed client uses the ADCs:

  namespace gcs = ::google::cloud::storage;
  [](std::string const& bucket_name, std::string const& object_name) {
    auto client = gcs::Client();
    PerformSomeOperations(client, bucket_name, object_name);
  }

Finding or loading the ADCs can fail. This will result in run-time errors when making requests.

If you prefer to explicitly load the ADCs use:

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::Options;
  using ::google::cloud::UnifiedCredentialsOption;
  [](std::string const& bucket_name, std::string const& object_name) {
    auto client = gcs::Client(Options{}.set<UnifiedCredentialsOption>(
        google::cloud::MakeGoogleDefaultCredentials()));
    PerformSomeOperations(client, bucket_name, object_name);
  }

To load a service account credentials key file use:

  namespace gcs = ::google::cloud::storage;
  [](std::string const& filename, std::string const& bucket_name,
     std::string const& object_name) {
    auto is = std::ifstream(filename);
    is.exceptions(std::ios::badbit);
    auto json_string =
        std::string(std::istreambuf_iterator<char>(is.rdbuf()), {});
    auto credentials =
        google::cloud::MakeServiceAccountCredentials(json_string);
    auto client = gcs::Client(
        google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
            credentials));
    PerformSomeOperations(client, bucket_name, object_name);
  }

Other credential types are available, including:

google::cloud::MakeInsecureCredentials() for anonymous access to public GCS buckets or objects.
google::cloud::MakeAccessTokenCredentials() to use an access token obtained through any out-of-band mechanism.
google::cloud::MakeImpersonateServiceAccountCredentials() to use the IAM credentials service and [impersonate a service account].
google::cloud::MakeServiceAccountCredentials() to use a service account key file.

Error Handling

This class uses StatusOr<T> to report errors. When an operation fails to perform its work the returned StatusOr<T> contains the error details. If the ok() member function in the StatusOr<T> returns true then it contains the expected result. Please consult the StatusOr<T> documentation for more details.

namespace gcs = google::cloud::storage;
gcs::Client client = ...;
google::cloud::StatusOr<gcs::BucketMetadata> bucket_metadata =
    client.GetBucketMetadata("my-bucket");

if (!bucket_metadata) {
  std::cerr << "Error getting metadata for my-bucket: "
            << bucket_metadata.status() << "\n";
  return;
}

// Use bucket_metadata as a smart pointer here, e.g.:
std::cout << "The generation for " << bucket_metadata->name() " is "
          << bucket_metadata->generation() << "\n";

In addition, the main page contains examples using StatusOr<T> to handle errors.

Optional Request Options

Most of the member functions in this class can receive optional request options. For example, the default when reading multi-version objects is to retrieve the latest version:

auto stream = gcs.ReadObject("my-bucket", "my-object");

Some applications may want to retrieve specific versions. In this case just provide the Generation request option:

auto stream = gcs.ReadObject(
    "my-bucket", "my-object", gcs::Generation(generation));

Each function documents the types accepted as optional request options. These parameters can be specified in any order. Specifying a request option that is not applicable to a member function results in a compile-time error.

All operations support the following common request options:

Fields: return a partial response, which includes only the desired fields.
QuotaUser: attribute the request to this specific label for quota purposes.
UserProject: change the request costs (if applicable) to this GCP project.
CustomHeader: include a custom header with the request. These are typically used for testing, though they are sometimes helpful if environments where HTTPS traffic is mediated by a proxy.
IfMatchEtag: a pre-condition, the operation succeeds only if the resource ETag matches. Typically used in OCC loops ("change X only if its Etag is still Y"). Note that GCS sometimes ignores this header, we recommend you use the GCS specific pre-conditions (e.g., IfGenerationMatch, IfMetagenerationMatch and their *NotMatch counterparts) instead.
IfNoneMatchEtag: a pre-condition, abort the operation if the resource ETag has not changed. Typically used in caching ("return the contents of X only if the Etag is different from the last value I got, which was Y"). Note that GCS sometimes ignores this header, we recommend you use the GCS specific pre-conditions (e.g., IfGenerationMatch, IfMetagenerationMatch and their *NotMatch counterparts) instead.
UserIp: attribute the request to this specific IP address for quota purpose. Not recommended, prefer QuotaUser instead.

Per-operation Overrides

In addition to the request options, which are passed on to the service to modify the request, you can specify options that override the local behavior of the library. For example, you can override the local retry policy:

  namespace g = ::google::cloud;
  namespace gcs = ::google::cloud::storage;
  [](std::string const& bucket_name, std::string const& object_name_1,
     std::string const& object_name_2) {
    auto client = gcs::Client();
    auto metadata = client.InsertObject(
        bucket_name, object_name_1,
        "The quick brown fox jumps over the lazy dog",
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedTimeRetryPolicy(std::chrono::minutes(5)).clone()));
    if (!metadata) throw std::move(metadata).status();

    auto is =
        client.ReadObject(bucket_name, object_name_1,
                          g::Options{}.set<gcs::RetryPolicyOption>(
                              gcs::LimitedErrorCountRetryPolicy(10).clone()));
    auto contents = std::string{std::istreambuf_iterator<char>(is.rdbuf()), {}};
    if (is.bad()) throw google::cloud::Status(is.status());

    auto os = client.WriteObject(
        bucket_name, object_name_2,
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedTimeRetryPolicy(std::chrono::minutes(5)).clone()));
    os << contents;
    os.Close();
    if (os.bad()) throw google::cloud::Status(os.metadata().status());

    auto result = client.DeleteObject(
        bucket_name, object_name_1, gcs::Generation(metadata->generation()),
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedErrorCountRetryPolicy(12).clone()));
    if (!result.ok()) throw std::move(metadata).status();

    metadata = os.metadata();
    result = client.DeleteObject(
        bucket_name, object_name_2, gcs::Generation(metadata->generation()),
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedErrorCountRetryPolicy(12).clone()));
    if (!result.ok()) throw std::move(metadata).status();
  }

Retry, Backoff, and Idempotency Policies

The library automatically retries requests that fail with transient errors, and follows the recommended practice to backoff between retries.

The default policies are to continue retrying for up to 15 minutes, and to use truncated (at 5 minutes) exponential backoff, doubling the maximum backoff period between retries. Likewise, the idempotency policy is configured to retry all operations.

The application can override these policies when constructing objects of this class. The documentation for the constructors show examples of this in action.

Constructors

Client(Options)

Build a new client.

Idempotency Policy Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](std::string const& bucket_name, std::string const& object_name,
     std::string const& contents) {
    // Create a client that only retries idempotent operations, the default is
    // to retry all operations.
    auto client =
        gcs::Client(google::cloud::Options{}.set<gcs::IdempotencyPolicyOption>(
            gcs::StrictIdempotencyPolicy().clone()));
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents),
                            gcs::IfGenerationMatch(0));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Modified Retry Policy Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](std::string const& bucket_name, std::string const& object_name,
     std::string const& contents) {
    // Create a client that only gives up on the third error. The default policy
    // is to retry for several minutes.
    auto client =
        gcs::Client(google::cloud::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedErrorCountRetryPolicy(3).clone()));

    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents),
                            gcs::IfGenerationMatch(0));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Change Credentials Example

  namespace gcs = ::google::cloud::storage;
  [](std::string const& filename, std::string const& bucket_name,
     std::string const& object_name) {
    auto is = std::ifstream(filename);
    is.exceptions(std::ios::badbit);
    auto json_string =
        std::string(std::istreambuf_iterator<char>(is.rdbuf()), {});
    auto credentials =
        google::cloud::MakeServiceAccountCredentials(json_string);
    auto client = gcs::Client(
        google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
            credentials));
    PerformSomeOperations(client, bucket_name, object_name);
  }

Parameter
Name	Description
`opts`	`Options` the configuration parameters for the `Client`.

Client(ClientOptions, Policies &&...)

Creates the default client type given the options.

Parameters
Name	Description
`options`	`ClientOptions` the client options, these are used to control credentials, buffer sizes, etc.
`policies`	`Policies &&...` the client policies, these control the behavior of the client, for example, how to backoff when an operation needs to be retried, or what operations cannot be retried because they are not idempotent.
`typename...`

Client(std::shared_ptr< oauth2::Credentials >, Policies &&...)

Creates the default client type given the credentials and policies.

Parameters
Name	Description
`credentials`	`std::shared_ptr< oauth2::Credentials >` a set of credentials to initialize the `ClientOptions`.
`policies`	`Policies &&...` the client policies, these control the behavior of the client, for example, how to backoff when an operation needs to be retried, or what operations cannot be retried because they are not idempotent.
`typename...`

Client(std::shared_ptr< internal::StorageConnection > const &, Policies &&...)

Builds a client and maybe override the retry, idempotency, and/or backoff policies.

Parameters
Name	Description
`connection`	`std::shared_ptr< internal::StorageConnection > const &`
`policies`	`Policies &&...`
`typename...`

Client(std::shared_ptr< internal::StorageConnection >, NoDecorations)

Builds a client with a specific StorageConnection, without decorations.

Parameters
Name	Description
`connection`	`std::shared_ptr< internal::StorageConnection >`
	`NoDecorations`

Functions

ListBucketsForProject(std::string const &, Options &&...)

Fetches the list of buckets for a given project.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& project_id) {
    int count = 0;
    for (auto&& bucket_metadata : client.ListBucketsForProject(project_id)) {
      if (!bucket_metadata) throw std::move(bucket_metadata).status();

      std::cout << bucket_metadata->name() << "\n";
      ++count;
    }

    if (count == 0) {
      std::cout << "No buckets in project " << project_id << "\n";
    }
  }

Parameters
Name	Description
`project_id`	`std::string const &` the project to query.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `MaxResults`, `Prefix`, `Projection`, and `UserProject`. `OverrideDefaultProject` is accepted, but has no effect.
`typename...`

Returns
Type	Description
`ListBucketsReader`

ListBuckets(Options &&...)

Fetches the list of buckets for the default project.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

Any parameters of type OverrideDefaultProject, with a value.
Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client) {
    int count = 0;
    gcs::ListBucketsReader bucket_list = client.ListBuckets();
    for (auto&& bucket_metadata : bucket_list) {
      if (!bucket_metadata) throw std::move(bucket_metadata).status();

      std::cout << bucket_metadata->name() << "\n";
      ++count;
    }

    if (count == 0) {
      std::cout << "No buckets in default project\n";
    }
  }

Parameters
Name	Description
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `MaxResults`, `Prefix`, `Projection`, `UserProject`, and `OverrideDefaultProject`.
`typename...`

Returns
Type	Description
`ListBucketsReader`

CreateBucket(std::string, BucketMetadata, Options &&...)

Creates a new Google Cloud Storage bucket using the default project.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

Any parameters of type OverrideDefaultProject, with a value.
Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This operation is always idempotent. It fails if the bucket already exists.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.CreateBucket(bucket_name, gcs::BucketMetadata());
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    std::cout << "Bucket " << bucket_metadata->name() << " created."
              << "\nFull Metadata: " << *bucket_metadata << "\n";
  }

CreateBucketForProject(std::string, std::string, BucketMetadata, Options &&...)

Creates a new Google Cloud Storage Bucket in a given project.

Idempotency

This operation is always idempotent. It fails if the bucket already exists.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& project_id) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.CreateBucketForProject(bucket_name, project_id,
                                      gcs::BucketMetadata{});
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    std::cout << "Bucket " << bucket_metadata->name() << " created for project "
              << project_id << " [" << bucket_metadata->project_number() << "]"
              << "\nFull Metadata: " << *bucket_metadata << "\n";
  }

GetBucketMetadata(std::string const &, Options &&...)

Fetches the bucket metadata.

Idempotency

This is a read-only operation and is always idempotent.

Example

  // [START storage_get_bucket_metadata]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.GetBucketMetadata(bucket_name);
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    std::cout << "The metadata for bucket " << bucket_metadata->name() << " is "
              << *bucket_metadata << "\n";
  }
  // [END storage_get_bucket_metadata]

Parameters
Name	Description
`bucket_name`	`std::string const &` query metadata information about this bucket.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `UserProject`, and `Projection`.
`typename...`

Returns
Type	Description
`StatusOr< BucketMetadata >`

DeleteBucket(std::string const &, Options &&...)

Deletes a Google Cloud Storage Bucket.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name) {
    google::cloud::Status status = client.DeleteBucket(bucket_name);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "The bucket " << bucket_name << " was deleted successfully.\n";
  }

Parameters
Name	Description
`bucket_name`	`std::string const &` the bucket to be deleted.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, and `UserProject`.
`typename...`

Returns
Type	Description
`Status`

UpdateBucket(std::string, BucketMetadata, Options &&...)

Updates the metadata in a Google Cloud Storage Bucket.

A Buckets: update request changes all the writeable attributes of a bucket, in contrast, a Buckets: patch request only changes the subset of the attributes included in the request. This function creates a Buckets: update request to change the writable attributes in BucketMetadata.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case,IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& storage_class) {
    StatusOr<gcs::BucketMetadata> meta = client.GetBucketMetadata(bucket_name);
    if (!meta) throw std::move(meta).status();

    meta->set_storage_class(storage_class);
    StatusOr<gcs::BucketMetadata> updated =
        client.UpdateBucket(bucket_name, *meta);
    if (!updated) throw std::move(updated).status();

    std::cout << "Updated the storage class in " << updated->name() << " to "
              << updated->storage_class() << "."
              << "\nFull metadata:" << *updated << "\n";
  }

PatchBucket(std::string, BucketMetadata const &, BucketMetadata const &, Options &&...)

Computes the difference between two BucketMetadata objects and patches a bucket based on that difference.

A Buckets: update request changes all the writeable attributes of a bucket, in contrast, a Buckets: patch request only changes the subset of the attributes included in the request.

This function creates a patch request to change the writeable attributes in original to the values in updated. Non-writeable attributes are ignored, and attributes not present in updated are removed. Typically this function is used after the application obtained a value with GetBucketMetadata and has modified these parameters.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& storage_class) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    gcs::BucketMetadata desired = *original;
    desired.set_storage_class(storage_class);

    StatusOr<gcs::BucketMetadata> patched =
        client.PatchBucket(bucket_name, *original, desired);
    if (!patched) throw std::move(patched).status();

    std::cout << "Storage class for bucket " << patched->name()
              << " has been patched to " << patched->storage_class() << "."
              << "\nFull metadata: " << *patched << "\n";
  }

PatchBucket(std::string, BucketMetadataPatchBuilder const &, Options &&...)

Patches the metadata in a Google Cloud Storage Bucket given a desired set changes.

A Buckets: update request changes all the writeable attributes of a bucket, in contrast, a Buckets: patch request only changes the subset of the attributes included in the request. This function creates a patch request based on the given BucketMetadataPatchBuilder which represents the desired set of changes.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& storage_class) {
    StatusOr<gcs::BucketMetadata> patched = client.PatchBucket(
        bucket_name,
        gcs::BucketMetadataPatchBuilder().SetStorageClass(storage_class));
    if (!patched) throw std::move(patched).status();

    std::cout << "Storage class for bucket " << patched->name()
              << " has been patched to " << patched->storage_class() << "."
              << "\nFull metadata: " << *patched << "\n";
  }

GetNativeBucketIamPolicy(std::string const &, Options &&...)

Fetches the native IAM policy for a Bucket.

Google Cloud Identity & Access Management (IAM) lets administrators authorize who can take action on specific resources, including Google Cloud Storage Buckets. This operation allows you to query the IAM policies for a Bucket. IAM policies are a superset of the Bucket ACL, changes to the Bucket ACL are reflected in the IAM policy, and vice-versa. The documentation describes the mapping between legacy Bucket ACLs and IAM policies.

Consult the documentation for a more detailed description of IAM policies and their use in Google Cloud Storage.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    auto policy = client.GetNativeBucketIamPolicy(
        bucket_name, gcs::RequestedPolicyVersion(3));

    if (!policy) throw std::move(policy).status();
    std::cout << "The IAM policy for bucket " << bucket_name << " is "
              << *policy << "\n";
  }

SetNativeBucketIamPolicy(std::string const &, NativeIamPolicy const &, Options &&...)

Sets the native IAM Policy for a Bucket.

Google Cloud Identity & Access Management (IAM) lets administrators authorize who can take action on specific resources, including Google Cloud Storage Buckets. This operation allows you to set the IAM policies for a Bucket. IAM policies are a superset of the Bucket ACL, changes to the Bucket ACL are reflected in the IAM policy, and vice-versa. The documentation describes the mapping between legacy Bucket ACLs and IAM policies.

Consult the documentation for a more detailed description of IAM policies their use in Google Cloud Storage.

Note: The server rejects requests where the ETag value of the policy does not match the current ETag. Effectively this means that applications must use GetNativeBucketIamPolicy() to fetch the current value and ETag before calling SetNativeBucketIamPolicy(). Applications should use optimistic concurrency control techniques to retry changes in case some other application modified the IAM policy between the GetNativeBucketIamPolicy and SetNativeBucketIamPolicy calls.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example: adding a new member

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& role, std::string const& member) {
    auto policy = client.GetNativeBucketIamPolicy(
        bucket_name, gcs::RequestedPolicyVersion(3));

    if (!policy) throw std::move(policy).status();

    policy->set_version(3);
    for (auto& binding : policy->bindings()) {
      if (binding.role() != role || binding.has_condition()) {
        continue;
      }
      auto& members = binding.members();
      if (std::find(members.begin(), members.end(), member) == members.end()) {
        members.emplace_back(member);
      }
    }

    auto updated = client.SetNativeBucketIamPolicy(bucket_name, *policy);
    if (!updated) throw std::move(updated).status();

    std::cout << "Updated IAM policy bucket " << bucket_name
              << ". The new policy is " << *updated << "\n";
  }

Example: removing a IAM member

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& role, std::string const& member) {
    auto policy = client.GetNativeBucketIamPolicy(
        bucket_name, gcs::RequestedPolicyVersion(3));
    if (!policy) throw std::move(policy).status();

    policy->set_version(3);
    std::vector<google::cloud::storage::NativeIamBinding> updated_bindings;
    for (auto& binding : policy->bindings()) {
      auto& members = binding.members();
      if (binding.role() == role && !binding.has_condition()) {
        members.erase(std::remove(members.begin(), members.end(), member),
                      members.end());
      }
      if (!members.empty()) {
        updated_bindings.emplace_back(std::move(binding));
      }
    }
    policy->bindings() = std::move(updated_bindings);

    auto updated = client.SetNativeBucketIamPolicy(bucket_name, *policy);
    if (!updated) throw std::move(updated).status();

    std::cout << "Updated IAM policy bucket " << bucket_name
              << ". The new policy is " << *updated << "\n";
  }

TestBucketIamPermissions(std::string, std::vector< std::string >, Options &&...)

Tests the IAM permissions of the caller against a Bucket.

Google Cloud Identity & Access Management (IAM) lets administrators authorize who can take action on specific resources, including Google Cloud Storage Buckets. This operation tests the permissions of the caller for a Bucket. You must provide a list of permissions, this API will return the subset of those permissions that the current caller has in the given Bucket.

Consult the documentation for a more detailed description of IAM policies their use in Google Cloud Storage.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::vector<std::string> const& permissions) {
    StatusOr<std::vector<std::string>> actual_permissions =
        client.TestBucketIamPermissions(bucket_name, permissions);
    if (!actual_permissions) throw std::move(actual_permissions).status();

    if (actual_permissions->empty()) {
      std::cout << "The caller does not hold any of the tested permissions the"
                << " bucket " << bucket_name << "\n";
      return;
    }

    std::cout << "The caller is authorized for the following permissions on "
              << bucket_name << ": ";
    for (auto const& permission : *actual_permissions) {
      std::cout << "\n    " << permission;
    }
    std::cout << "\n";
  }

Parameters
Name	Description
`bucket_name`	`std::string` query metadata information about this bucket.
`permissions`	`std::vector< std::string >` the list of permissions to check.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `UserProject`.
`typename...`

Returns
Type	Description
`StatusOr< std::vector< std::string > >`

LockBucketRetentionPolicy(std::string const &, std::uint64_t, Options &&...)

Locks the retention policy for a bucket.

The Bucket Lock feature allows you to configure a data retention policy for a Cloud Storage bucket that governs how long objects in the bucket must be retained. The feature also allows you to lock the data retention policy, permanently preventing the policy from being reduced or removed.

Idempotency

This operation is always idempotent because the metageneration parameter is always required, and it acts as a pre-condition on the operation.

Example: lock the retention policy

  // [START storage_lock_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    StatusOr<gcs::BucketMetadata> updated_metadata =
        client.LockBucketRetentionPolicy(bucket_name,
                                         original->metageneration());
    if (!updated_metadata) throw std::move(updated_metadata).status();

    if (!updated_metadata->has_retention_policy()) {
      std::cerr << "The bucket " << updated_metadata->name()
                << " does not have a retention policy, even though the"
                << " operation to set it was successful.\n"
                << "This is unexpected, and may indicate that another"
                << " application has modified the bucket concurrently.\n";
      return;
    }

    std::cout << "Retention policy successfully locked for bucket "
              << updated_metadata->name() << "\nNew retention policy is: "
              << updated_metadata->retention_policy()
              << "\nFull metadata: " << *updated_metadata << "\n";
  }
  // [END storage_lock_retention_policy]

Example: get the current retention policy

  // [START storage_get_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.GetBucketMetadata(bucket_name);
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    if (!bucket_metadata->has_retention_policy()) {
      std::cout << "The bucket " << bucket_metadata->name()
                << " does not have a retention policy set.\n";
      return;
    }

    std::cout << "The bucket " << bucket_metadata->name()
              << " retention policy is set to "
              << bucket_metadata->retention_policy() << "\n";
  }
  // [END storage_get_retention_policy]

Example: set the current retention policy

  // [START storage_set_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::chrono::seconds period) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    StatusOr<gcs::BucketMetadata> patched = client.PatchBucket(
        bucket_name,
        gcs::BucketMetadataPatchBuilder().SetRetentionPolicy(period),
        gcs::IfMetagenerationMatch(original->metageneration()));
    if (!patched) throw std::move(patched).status();

    if (!patched->has_retention_policy()) {
      std::cout << "The bucket " << patched->name()
                << " does not have a retention policy set.\n";
      return;
    }

    std::cout << "The bucket " << patched->name()
              << " retention policy is set to " << patched->retention_policy()
              << "\n";
  }
  // [END storage_set_retention_policy]

Example: remove the retention policy

  // [START storage_remove_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    StatusOr<gcs::BucketMetadata> patched = client.PatchBucket(
        bucket_name, gcs::BucketMetadataPatchBuilder().ResetRetentionPolicy(),
        gcs::IfMetagenerationMatch(original->metageneration()));
    if (!patched) throw std::move(patched).status();

    if (!patched->has_retention_policy()) {
      std::cout << "The bucket " << patched->name()
                << " does not have a retention policy set.\n";
      return;
    }

    std::cout << "The bucket " << patched->name()
              << " retention policy is set to " << patched->retention_policy()
              << ". This is unexpected, maybe a concurrent change by another"
              << " application?\n";
  }
  // [END storage_remove_retention_policy]

InsertObject(std::string const &, std::string const &, absl::string_view, Options &&...)

Creates an object given its name and contents.

If you need to perform larger uploads or uploads where the data is not contiguous in memory, use WriteObject(). This function always performs a single-shot upload, while WriteObject() always uses resumable uploads. The service documentation has recommendations on the upload size vs. single-shot or resumable uploads.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& contents) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type,
     std::string const& contents) {
    // Setting the object metadata (via the `gcs::WithObjectMadata` option)
    // requires a multipart upload, the library prefers simple uploads unless
    // required as in this case.
    StatusOr<gcs::ObjectMetadata> object_metadata = client.InsertObject(
        bucket_name, object_name, std::move(contents),
        gcs::WithObjectMetadata(
            gcs::ObjectMetadata().set_content_type(content_type)));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nThe contentType was set to "
              << object_metadata->content_type()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters
Name	Description
`bucket_name`	`std::string const &` the name of the bucket that will contain the object.
`object_name`	`std::string const &` the name of the object to be created.
`contents`	`absl::string_view` the contents (media) for the new object.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `ContentEncoding`, `ContentType`, `Crc32cChecksumValue`, `DisableCrc32cChecksum`, `DisableMD5Hash`, `EncryptionKey`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `KmsKeyName`, `MD5HashValue`, `PredefinedAcl`, `Projection`, `UserProject`, and `WithObjectMetadata`.
`typename...`

Returns
Type	Description
`StatusOr< ObjectMetadata >`

InsertObject(std::string const &, std::string const &, std::string const &, Options &&...)

Creates an object given its name and contents.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& contents) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type,
     std::string const& contents) {
    // Setting the object metadata (via the `gcs::WithObjectMadata` option)
    // requires a multipart upload, the library prefers simple uploads unless
    // required as in this case.
    StatusOr<gcs::ObjectMetadata> object_metadata = client.InsertObject(
        bucket_name, object_name, std::move(contents),
        gcs::WithObjectMetadata(
            gcs::ObjectMetadata().set_content_type(content_type)));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nThe contentType was set to "
              << object_metadata->content_type()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters
Name	Description
`bucket_name`	`std::string const &` the name of the bucket that will contain the object.
`object_name`	`std::string const &` the name of the object to be created.
`contents`	`std::string const &` the contents (media) for the new object.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `ContentEncoding`, `ContentType`, `Crc32cChecksumValue`, `DisableCrc32cChecksum`, `DisableMD5Hash`, `EncryptionKey`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `KmsKeyName`, `MD5HashValue`, `PredefinedAcl`, `Projection`, `UserProject`, and `WithObjectMetadata`.
`typename...`

Returns
Type	Description
`StatusOr< ObjectMetadata >`

InsertObject(std::string const &, std::string const &, char const *, Options &&...)

Creates an object given its name and contents.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& contents) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type,
     std::string const& contents) {
    // Setting the object metadata (via the `gcs::WithObjectMadata` option)
    // requires a multipart upload, the library prefers simple uploads unless
    // required as in this case.
    StatusOr<gcs::ObjectMetadata> object_metadata = client.InsertObject(
        bucket_name, object_name, std::move(contents),
        gcs::WithObjectMetadata(
            gcs::ObjectMetadata().set_content_type(content_type)));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nThe contentType was set to "
              << object_metadata->content_type()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters
Name	Description
`bucket_name`	`std::string const &` the name of the bucket that will contain the object.
`object_name`	`std::string const &` the name of the object to be created.
`contents`	`char const *` the contents (media) for the new object.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `ContentEncoding`, `ContentType`, `Crc32cChecksumValue`, `DisableCrc32cChecksum`, `DisableMD5Hash`, `EncryptionKey`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `KmsKeyName`, `MD5HashValue`, `PredefinedAcl`, `Projection`, `UserProject`, and `WithObjectMetadata`.
`typename...`

Returns
Type	Description
`StatusOr< ObjectMetadata >`

CopyObject(std::string, std::string, std::string, std::string, Options &&...)

Copies an existing object.

Use CopyObject to copy between objects in the same location and storage class. Copying objects across locations or storage classes can fail for large objects and retrying the operation will not succeed.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name) {
    StatusOr<gcs::ObjectMetadata> new_copy_meta =
        client.CopyObject(source_bucket_name, source_object_name,
                          destination_bucket_name, destination_object_name);
    if (!new_copy_meta) throw std::move(new_copy_meta).status();

    std::cout << "Successfully copied " << source_object_name << " in bucket "
              << source_bucket_name << " to bucket " << new_copy_meta->bucket()
              << " with name " << new_copy_meta->name()
              << ".\nThe full metadata after the copy is: " << *new_copy_meta
              << "\n";
  }

Example: copy an encrypted object

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name,
     std::string const& key_base64) {
    StatusOr<gcs::ObjectMetadata> new_copy_meta = client.CopyObject(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name, gcs::EncryptionKey::FromBase64Key(key_base64));
    if (!new_copy_meta) throw std::move(new_copy_meta).status();

    std::cout << "Successfully copied " << source_object_name << " in bucket "
              << source_bucket_name << " to bucket " << new_copy_meta->bucket()
              << " with name " << new_copy_meta->name()
              << ".\nThe full metadata after the copy is: " << *new_copy_meta
              << "\n";
  }

GetObjectMetadata(std::string const &, std::string const &, Options &&...)

Fetches the object metadata.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.GetObjectMetadata(bucket_name, object_name);
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The metadata for object " << object_metadata->name()
              << " in bucket " << object_metadata->bucket() << " is "
              << *object_metadata << "\n";
  }

Parameters
Name	Description
`bucket_name`	`std::string const &` the bucket containing the object.
`object_name`	`std::string const &` the object name.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `Generation`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `Projection`, and `UserProject`.
`typename...`

Returns
Type	Description
`StatusOr< ObjectMetadata >`

ListObjects(std::string const &, Options &&...)

Lists the objects in a bucket.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name) {
    for (auto&& object_metadata : client.ListObjects(bucket_name)) {
      if (!object_metadata) throw std::move(object_metadata).status();

      std::cout << "bucket_name=" << object_metadata->bucket()
                << ", object_name=" << object_metadata->name() << "\n";
    }
  }

Parameters
Name	Description
`bucket_name`	`std::string const &` the name of the bucket to list.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `MaxResults`, `Prefix`, `Delimiter`, `IncludeTrailingDelimiter`, `StartOffset`, `EndOffset`, `MatchGlob`, `Projection`, `UserProject`, and `Versions`.
`typename...`

Returns
Type	Description
`ListObjectsReader`

ListObjectsAndPrefixes(std::string const &, Options &&...)

Lists the objects and prefixes in a bucket.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& bucket_prefix) {
    for (auto&& item : client.ListObjectsAndPrefixes(
             bucket_name, gcs::Prefix(bucket_prefix), gcs::Delimiter("/"))) {
      if (!item) throw std::move(item).status();
      auto result = *std::move(item);
      if (absl::holds_alternative<gcs::ObjectMetadata>(result)) {
        std::cout << "object_name="
                  << absl::get<gcs::ObjectMetadata>(result).name() << "\n";
      } else if (absl::holds_alternative<std::string>(result)) {
        std::cout << "prefix     =" << absl::get<std::string>(result) << "\n";
      }
    }
  }

Parameters
Name	Description
`bucket_name`	`std::string const &` the name of the bucket to list.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `UserProject`, `Projection`, `Prefix`, `Delimiter`, `IncludeTrailingDelimiter`, `StartOffset`, `EndOffset`, `MatchGlob`, and `Versions`.
`typename...`

Returns
Type	Description
`ListObjectsAndPrefixesReader`

ReadObject(std::string const &, std::string const &, Options &&...)

Reads the contents of an object.

Returns an object derived from std::istream which can be used to read the contents of the GCS blob. The application should check the badbit (e.g. by calling stream.bad()) on the returned object to detect if there was an error reading from the blob. If badbit is set, the application can check the status() variable to get details about the failure. Applications can also set the exception mask on the returned stream, in which case an exception is thrown if an error is detected.

Idempotency

This is a read-only operation and is always idempotent.

Example

  // [START storage_stream_file_download]
  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    gcs::ObjectReadStream stream = client.ReadObject(bucket_name, object_name);

    int count = 0;
    std::string line;
    while (std::getline(stream, line, '\n')) {
      ++count;
    }
    if (stream.bad()) throw google::cloud::Status(stream.status());

    std::cout << "The object has " << count << " lines\n";
  }
  // [END storage_stream_file_download]

Example: read only a sub-range in the object.

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::int64_t start, std::int64_t end) {
    gcs::ObjectReadStream stream =
        client.ReadObject(bucket_name, object_name, gcs::ReadRange(start, end));

    int count = 0;
    std::string line;
    while (std::getline(stream, line, '\n')) {
      std::cout << line << "\n";
      ++count;
    }
    if (stream.bad()) throw google::cloud::Status(stream.status());

    std::cout << "The requested range has " << count << " lines\n";
  }

Example: read a object encrypted with a CSEK.

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& base64_aes256_key) {
    gcs::ObjectReadStream stream =
        client.ReadObject(bucket_name, object_name,
                          gcs::EncryptionKey::FromBase64Key(base64_aes256_key));

    std::string data(std::istreambuf_iterator<char>{stream}, {});
    if (stream.bad()) throw google::cloud::Status(stream.status());
    std::cout << "The object contents are: " << data << "\n";
  }

Example: disable decompressive transcoding.

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    auto is =
        client.ReadObject(bucket_name, object_name, gcs::AcceptEncodingGzip());
    auto const contents = std::string{std::istream_iterator<char>(is), {}};
    if (is.bad()) throw google::cloud::Status(is.status());
    std::cout << "The object has " << contents.size() << " characters\n";
  }

Parameters
Name	Description
`bucket_name`	`std::string const &` the name of the bucket that contains the object.
`object_name`	`std::string const &` the name of the object to be read.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `DisableCrc32cChecksum`, `DisableMD5Hash`, `EncryptionKey`, `Generation`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `ReadFromOffset`, `ReadRange`, `ReadLast`, `UserProject`, and `AcceptEncoding`.
`typename...`

Returns
Type	Description
`ObjectReadStream`

WriteObject(std::string const &, std::string const &, Options &&...)

Writes contents into an object.

This creates a std::ostream object to upload contents. The application can use either the regular operator<<(), or std::ostream::write() to upload data.

For small uploads where all the data is contiguous in memory we recommend using InsertObject(). The service documentation has specific recommendations on object sizes and upload types.

This function always uses resumable uploads. The application can provide a #RestoreResumableUploadSession() option to resume a previously created upload. The returned object has accessors to query the session id and the next byte expected by GCS.

If the application does not provide a #RestoreResumableUploadSession() option, or it provides the #NewResumableUploadSession() option then a new resumable upload session is created.

More information about buffering and recommendations around performance in the ObjectWriteStream class documentation.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, int desired_line_count) {
    std::string const text = "Lorem ipsum dolor sit amet";
    gcs::ObjectWriteStream stream =
        client.WriteObject(bucket_name, object_name);

    for (int lineno = 0; lineno != desired_line_count; ++lineno) {
      // Add 1 to the counter, because it is conventional to number lines
      // starting at 1.
      stream << (lineno + 1) << ": " << text << "\n";
    }

    stream.Close();

    StatusOr<gcs::ObjectMetadata> metadata = std::move(stream).metadata();
    if (!metadata) throw std::move(metadata).status();
    std::cout << "Successfully wrote to object " << metadata->name()
              << " its size is: " << metadata->size()
              << "\nFull metadata: " << *metadata << "\n";
  }

Example: write an object with a CMEK.

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& kms_key_name) {
    gcs::ObjectWriteStream stream = client.WriteObject(
        bucket_name, object_name, gcs::KmsKeyName(kms_key_name));

    // Line numbers start at 1.
    for (int lineno = 1; lineno <= 10; ++lineno) {
      stream << lineno << ": placeholder text for CMEK example.\n";
    }

    stream.Close();

    StatusOr<gcs::ObjectMetadata> metadata = std::move(stream).metadata();
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Successfully wrote to object " << metadata->name()
              << " its size is: " << metadata->size()
              << "\nFull metadata: " << *metadata << "\n";
  }

Example: starting a resumable upload.

  namespace gcs = ::google::cloud::storage;
  return [](gcs::Client client, std::string const& bucket_name,
            std::string const& object_name) {
    gcs::ObjectWriteStream stream = client.WriteObject(
        bucket_name, object_name, gcs::NewResumableUploadSession(),
        gcs::AutoFinalizeDisabled());
    auto session_id = stream.resumable_session_id();
    std::cout << "Created resumable upload: " << session_id << "\n";
    // Because this stream was created with `AutoFinalizeDisabled()` its
    // destructor will *not* finalize the upload, allowing a separate process or
    // function to resume and continue the upload.
    stream << "This data will not get uploaded, it is too small\n";
    return session_id;
  }

Example: resuming a resumable upload.

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& session_id) {
    // Restore a resumable upload stream, the library automatically queries the
    // state of the upload and discovers the next expected byte.
    gcs::ObjectWriteStream stream =
        client.WriteObject(bucket_name, object_name,
                           gcs::RestoreResumableUploadSession(session_id));
    if (!stream.IsOpen() && stream.metadata().ok()) {
      std::cout << "The upload has already been finalized.  The object "
                << "metadata is: " << *stream.metadata() << "\n";
    }
    if (stream.next_expected_byte() == 0) {
      // In this example we create a small object, smaller than the resumable
      // upload quantum (256 KiB), so either all the data is there or not.
      // Applications use `next_expected_byte()` to find the position in their
      // input where they need to start uploading.
      stream << R"""(
Lorem ipsum dolor sit amet, consectetur adipiscing
elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim
ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea
commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit
esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat
non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
)""";
    }

    stream.Close();

    StatusOr<gcs::ObjectMetadata> metadata = stream.metadata();
    if (!metadata) throw std::move(metadata).status();
    std::cout << "Upload completed, the new object metadata is: " << *metadata
              << "\n";
  }

UploadFile(std::string const &, std::string const &, std::string const &, Options &&...)

Uploads a file to an object.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& file_name,
     std::string const& bucket_name, std::string const& object_name) {
    // Note that the client library automatically computes a hash on the
    // client-side to verify data integrity during transmission.
    StatusOr<gcs::ObjectMetadata> metadata = client.UploadFile(
        file_name, bucket_name, object_name, gcs::IfGenerationMatch(0));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Uploaded " << file_name << " to object " << metadata->name()
              << " in bucket " << metadata->bucket()
              << "\nFull metadata: " << *metadata << "\n";
  }

Example: manually selecting a resumable upload

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& file_name,
     std::string const& bucket_name, std::string const& object_name) {
    // Note that the client library automatically computes a hash on the
    // client-side to verify data integrity during transmission.
    StatusOr<gcs::ObjectMetadata> metadata = client.UploadFile(
        file_name, bucket_name, object_name, gcs::IfGenerationMatch(0),
        gcs::NewResumableUploadSession());
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Uploaded " << file_name << " to object " << metadata->name()
              << " in bucket " << metadata->bucket()
              << "\nFull metadata: " << *metadata << "\n";
  }

Parameters
Name	Description
`file_name`	`std::string const &` the name of the file to be uploaded.
`bucket_name`	`std::string const &` the name of the bucket that contains the object.
`object_name`	`std::string const &` the name of the object to be read.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `ContentEncoding`, `ContentType`, `Crc32cChecksumValue`, `DisableCrc32cChecksum`, `DisableMD5Hash`, `EncryptionKey`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `KmsKeyName`, `MD5HashValue`, `PredefinedAcl`, `Projection`, `UserProject`, `UploadFromOffset`, `UploadLimit` and `WithObjectMetadata`.
`typename...`

Returns
Type	Description
`StatusOr< ObjectMetadata >`

DeleteResumableUpload(std::string const &, Options &&...)

Cancel a resumable upload.

Idempotency

This operation is always idempotent because it only acts on a specific upload_session_url.

Parameters
Name	Description
`upload_session_url`	`std::string const &` the url of the upload session. Returned by `ObjectWriteStream::resumable_session_id`.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `UserProject`.
`typename...`

Returns
Type	Description
`Status`

DownloadToFile(std::string const &, std::string const &, std::string const &, Options &&...)

Downloads a Cloud Storage object to a file.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& file_name) {
    google::cloud::Status status =
        client.DownloadToFile(bucket_name, object_name, file_name);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "Downloaded " << object_name << " to " << file_name << "\n";
  }

Parameters
Name	Description
`bucket_name`	`std::string const &` the name of the bucket that contains the object.
`object_name`	`std::string const &` the name of the object to be downloaded.
`file_name`	`std::string const &` the name of the destination file that will have the object media.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `Generation`, `ReadFromOffset`, `ReadRange`, and `UserProject`.
`typename...`

Returns
Type	Description
`Status`

DeleteObject(std::string const &, std::string const &, Options &&...)

Deletes an object.

Idempotency

This operation is only idempotent if:

restricted by pre-conditions, in this case, IfGenerationMatch
or, if it applies to only one object version via Generation.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    google::cloud::Status status =
        client.DeleteObject(bucket_name, object_name);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted " << object_name << " in bucket " << bucket_name
              << "\n";
  }

Parameters
Name	Description
`bucket_name`	`std::string const &` the name of the bucket that contains the object.
`object_name`	`std::string const &` the name of the object to be deleted.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `Generation`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, and `UserProject`.
`typename...`

Returns
Type	Description
`Status`

UpdateObject(std::string, std::string, ObjectMetadata, Options &&...)

Updates the metadata in a Google Cloud Storage Object.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& key,
     std::string const& value) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.GetObjectMetadata(bucket_name, object_name);
    if (!object_metadata) throw std::move(object_metadata).status();

    gcs::ObjectMetadata desired = *object_metadata;
    desired.mutable_metadata().emplace(key, value);

    StatusOr<gcs::ObjectMetadata> updated =
        client.UpdateObject(bucket_name, object_name, desired,
                            gcs::Generation(object_metadata->generation()));

    if (!updated) throw std::move(updated).status();
    std::cout << "Object updated. The full metadata after the update is: "
              << *updated << "\n";
  }

Parameters
Name	Description
`bucket_name`	`std::string` the name of the bucket that contains the object.
`object_name`	`std::string` the name of the object.
`metadata`	`ObjectMetadata` the new metadata for the Object. Only the writeable fields accepted by the `Objects: update` API are used, all other fields are ignored. In particular, note that `bucket` and `name` are ignored in favor of `bucket_name` and `object_name`.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `Generation`, `EncryptionKey`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `PredefinedAcl`, `Projection`, and `UserProject`.
`typename...`

Returns
Type	Description
`StatusOr< ObjectMetadata >`

PatchObject(std::string, std::string, ObjectMetadata const &, ObjectMetadata const &, Options &&...)

Patches the metadata in a Google Cloud Storage Object.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& key) {
    StatusOr<gcs::ObjectMetadata> original =
        client.GetObjectMetadata(bucket_name, object_name);

    if (!original) throw std::move(original).status();
    gcs::ObjectMetadata desired = *original;
    desired.mutable_metadata().erase(key);

    StatusOr<gcs::ObjectMetadata> updated =
        client.PatchObject(bucket_name, object_name, *original, desired);

    if (!updated) throw std::move(updated).status();
    std::cout << "Object updated. The full metadata after the update is: "
              << *updated << "\n";
  }

Parameters
Name	Description
`bucket_name`	`std::string` the bucket that contains the object to be updated.
`object_name`	`std::string` the object to be updated.
`original`	`ObjectMetadata const &` the initial value of the object metadata.
`updated`	`ObjectMetadata const &` the updated value for the object metadata.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `Generation`, `EncryptionKey`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `PredefinedAcl`, `Projection`, and `UserProject`.
`typename...`

Returns
Type	Description
`StatusOr< ObjectMetadata >`

PatchObject(std::string, std::string, ObjectMetadataPatchBuilder const &, Options &&...)

Patches the metadata in a Google Cloud Storage Object.

This function creates a patch request based on the given builder. Typically this function is used when the application needs to set an object's metadata fields regardless of their previous value (i.e. when calling GetObjectMetadata first is not necessary).

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type) {
    StatusOr<gcs::ObjectMetadata> updated = client.PatchObject(
        bucket_name, object_name,
        gcs::ObjectMetadataPatchBuilder().SetContentType(content_type));

    if (!updated) throw std::move(updated).status();
    std::cout << "Object updated. The full metadata after the update is: "
              << *updated << "\n";
  }

Parameters
Name	Description
`bucket_name`	`std::string` the bucket that contains the object to be updated.
`object_name`	`std::string` the object to be updated.
`builder`	`ObjectMetadataPatchBuilder const &` the set of updates to perform in the Object metadata.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `Generation`, `EncryptionKey`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfMetagenerationNotMatch`, `PredefinedAcl`, `EncryptionKey`, `Projection`, and `UserProject`.
`typename...`

Returns
Type	Description
`StatusOr< ObjectMetadata >`

ComposeObject(std::string, std::vector< ComposeSourceObject >, std::string, Options &&...)

Composes existing objects into a new object in the same bucket.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& destination_object_name,
     std::vector<gcs::ComposeSourceObject> const& compose_objects) {
    StatusOr<gcs::ObjectMetadata> composed_object = client.ComposeObject(
        bucket_name, compose_objects, destination_object_name);
    if (!composed_object) throw std::move(composed_object).status();

    std::cout << "Composed new object " << composed_object->name()
              << " in bucket " << composed_object->bucket()
              << "\nFull metadata: " << *composed_object << "\n";
  }

Example: using encrypted objects with CSEK

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& destination_object_name,
     std::string const& base64_aes256_key,
     std::vector<gcs::ComposeSourceObject> const& compose_objects) {
    StatusOr<gcs::ObjectMetadata> composed_object = client.ComposeObject(
        bucket_name, compose_objects, destination_object_name,
        gcs::EncryptionKey::FromBase64Key(base64_aes256_key));
    if (!composed_object) throw std::move(composed_object).status();

    std::cout << "Composed new object " << composed_object->name()
              << " in bucket " << composed_object->bucket()
              << "\nFull metadata: " << *composed_object << "\n";
  }

Parameters
Name	Description
`bucket_name`	`std::string` the name of the bucket used for source object and destination object.
`source_objects`	`std::vector< ComposeSourceObject >` objects used to compose `destination_object_name`.
`destination_object_name`	`std::string` the composed object name.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `DestinationPredefinedAcl`, `EncryptionKey`, `IfGenerationMatch`, `IfMetagenerationMatch`, `KmsKeyName`, `UserProject`, and `WithObjectMetadata`.
`typename...`

Returns
Type	Description
`StatusOr< ObjectMetadata >`

RewriteObject(std::string, std::string, std::string, std::string, Options &&...)

Creates an ObjectRewriter to copy the source object.

Applications use this function to reliably copy objects across location boundaries, and to rewrite objects with different encryption keys. The operation returns a ObjectRewriter, which the application can use to initiate the copy and to iterate if the copy requires more than one call to complete.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name) {
    gcs::ObjectRewriter rewriter =
        client.RewriteObject(source_bucket_name, source_object_name,
                             destination_bucket_name, destination_object_name);

    auto callback = [](StatusOr<gcs::RewriteProgress> progress) {
      if (!progress) throw std::move(progress).status();
      std::cout << "Rewrote " << progress->total_bytes_rewritten << "/"
                << progress->object_size << "\n";
    };
    StatusOr<gcs::ObjectMetadata> metadata =
        rewriter.ResultWithProgressCallback(std::move(callback));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << metadata->name() << " in bucket "
              << metadata->bucket() << "\nFull Metadata: " << *metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name,
     std::string const& rewrite_token) {
    gcs::ObjectRewriter rewriter = client.ResumeRewriteObject(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name, rewrite_token,
        gcs::MaxBytesRewrittenPerCall(1024 * 1024));

    auto callback = [](StatusOr<gcs::RewriteProgress> progress) {
      if (!progress) throw std::move(progress).status();
      std::cout << "Rewrote " << progress->total_bytes_rewritten << "/"
                << progress->object_size << "\n";
    };
    StatusOr<gcs::ObjectMetadata> metadata =
        rewriter.ResultWithProgressCallback(std::move(callback));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << metadata->name() << " in bucket "
              << metadata->bucket() << "\nFull Metadata: " << *metadata << "\n";
  }

Parameters
Name	Description
`source_bucket_name`	`std::string` the name of the bucket containing the source object.
`source_object_name`	`std::string` the name of the source object.
`destination_bucket_name`	`std::string` where the destination object will be located.
`destination_object_name`	`std::string` what to name the destination object.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `DestinationKmsKeyName`, `DestinationPredefinedAcl`, `EncryptionKey`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfSourceGenerationMatch`, `IfSourceGenerationNotMatch`, `IfSourceMetagenerationMatch`, `IfSourceMetagenerationNotMatch`, `MaxBytesRewrittenPerCall`, `Projection`, `SourceEncryptionKey`, `SourceGeneration`, `UserProject`, and `WithObjectMetadata`.
`typename...`

Returns
Type	Description
`ObjectRewriter`

ResumeRewriteObject(std::string, std::string, std::string, std::string, std::string, Options &&...)

Creates an ObjectRewriter to resume a previously created rewrite.

Applications use this function to resume a rewrite operation, possibly created with RewriteObject(). Rewrite can reliably copy objects across location boundaries, and can rewrite objects with different encryption keys. For large objects this operation can take a long time, thus applications should consider checkpointing the rewrite token (accessible in the ObjectRewriter) and restarting the operation in the event the program is terminated.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name,
     std::string const& rewrite_token) {
    gcs::ObjectRewriter rewriter = client.ResumeRewriteObject(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name, rewrite_token,
        gcs::MaxBytesRewrittenPerCall(1024 * 1024));

    auto callback = [](StatusOr<gcs::RewriteProgress> progress) {
      if (!progress) throw std::move(progress).status();
      std::cout << "Rewrote " << progress->total_bytes_rewritten << "/"
                << progress->object_size << "\n";
    };
    StatusOr<gcs::ObjectMetadata> metadata =
        rewriter.ResultWithProgressCallback(std::move(callback));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << metadata->name() << " in bucket "
              << metadata->bucket() << "\nFull Metadata: " << *metadata << "\n";
  }

Parameters
Name	Description
`source_bucket_name`	`std::string` the name of the bucket containing the source object.
`source_object_name`	`std::string` the name of the source object.
`destination_bucket_name`	`std::string` where the destination object will be located.
`destination_object_name`	`std::string` what to name the destination object.
`rewrite_token`	`std::string` the token from a previous successful rewrite iteration. Can be the empty string, in which case this starts a new rewrite operation.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `DestinationKmsKeyName`, `DestinationPredefinedAcl`, `EncryptionKey`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfSourceGenerationMatch`, `IfSourceGenerationNotMatch`, `IfSourceMetagenerationMatch`, `IfSourceMetagenerationNotMatch`, `MaxBytesRewrittenPerCall`, `Projection`, `SourceEncryptionKey`, `SourceGeneration`, `UserProject`, and `WithObjectMetadata`.
`typename...`

Returns
Type	Description
`ObjectRewriter`

RewriteObjectBlocking(std::string, std::string, std::string, std::string, Options &&...)

Rewrites the object, blocking until the rewrite completes, and returns the resulting ObjectMetadata.

Applications use this function to reliably copy objects across location boundaries, and to rewrite objects with different encryption keys. The operation blocks until the rewrite completes, and returns the resulting ObjectMetadata.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name) {
    StatusOr<gcs::ObjectMetadata> metadata = client.RewriteObjectBlocking(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name);
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << destination_object_name
              << " Metadata: " << *metadata << "\n";
  }

Example: using rewrite object to rotate the encryption key

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& old_key_base64,
     std::string const& new_key_base64) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.RewriteObjectBlocking(
            bucket_name, object_name, bucket_name, object_name,
            gcs::SourceEncryptionKey::FromBase64Key(old_key_base64),
            gcs::EncryptionKey::FromBase64Key(new_key_base64));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "Rotated key on object " << object_metadata->name()
              << " in bucket " << object_metadata->bucket()
              << "\nFull Metadata: " << *object_metadata << "\n";
  }

Example: using rewrite object to rename an object

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& old_object_name, std::string const& new_object_name) {
    StatusOr<gcs::ObjectMetadata> metadata = client.RewriteObjectBlocking(
        bucket_name, old_object_name, bucket_name, new_object_name);
    if (!metadata) throw std::move(metadata).status();

    google::cloud::Status status =
        client.DeleteObject(bucket_name, old_object_name);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "Renamed " << old_object_name << " to " << new_object_name
              << " in bucket " << bucket_name << "\n";
  }

Parameters
Name	Description
`source_bucket_name`	`std::string` the name of the bucket containing the source object.
`source_object_name`	`std::string` the name of the source object.
`destination_bucket_name`	`std::string` where the destination object will be located.
`destination_object_name`	`std::string` what to name the destination object.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `DestinationKmsKeyName`, `DestinationPredefinedAcl`, `EncryptionKey`, `IfGenerationMatch`, `IfGenerationNotMatch`, `IfMetagenerationMatch`, `IfSourceGenerationMatch`, `IfSourceGenerationNotMatch`, `IfSourceMetagenerationMatch`, `IfSourceMetagenerationNotMatch`, `MaxBytesRewrittenPerCall`, `Projection`, `SourceEncryptionKey`, `SourceGeneration`, `UserProject`, and `WithObjectMetadata`.
`typename...`

Returns
Type	Description
`StatusOr< ObjectMetadata >`	The metadata of the newly created object.

ListBucketAcl(std::string const &, Options &&...)

Retrieves the list of BucketAccessControl items for a bucket.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<std::vector<gcs::BucketAccessControl>> items =
        client.ListBucketAcl(bucket_name);

    if (!items) throw std::move(items).status();
    std::cout << "ACLs for bucket=" << bucket_name << "\n";
    for (gcs::BucketAccessControl const& acl : *items) {
      std::cout << acl.role() << ":" << acl.entity() << "\n";
    }
  }

Parameters
Name	Description
`bucket_name`	`std::string const &` the name of the bucket.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `UserProject`.
`typename...`

Returns
Type	Description
`StatusOr< std::vector< BucketAccessControl > >`

CreateBucketAcl(std::string const &, std::string const &, std::string const &, Options &&...)

Creates a new entry in a bucket ACL.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::BucketAccessControl> bucket_acl =
        client.CreateBucketAcl(bucket_name, entity, role);

    if (!bucket_acl) throw std::move(bucket_acl).status();
    std::cout << "Role " << bucket_acl->role() << " granted to "
              << bucket_acl->entity() << " on bucket " << bucket_acl->bucket()
              << "\n"
              << "Full attributes: " << *bucket_acl << "\n";
  }

DeleteBucketAcl(std::string const &, std::string const &, Options &&...)

Deletes an entry from a bucket ACL.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    google::cloud::Status status = client.DeleteBucketAcl(bucket_name, entity);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted ACL entry for " << entity << " in bucket "
              << bucket_name << "\n";
  }

GetBucketAcl(std::string const &, std::string const &, Options &&...)

Gets the value of an existing bucket ACL.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    StatusOr<gcs::BucketAccessControl> acl =
        client.GetBucketAcl(bucket_name, entity);

    if (!acl) throw std::move(acl).status();
    std::cout << "ACL entry for " << acl->entity() << " in bucket "
              << acl->bucket() << " is " << *acl << "\n";
  }

UpdateBucketAcl(std::string const &, BucketAccessControl const &, Options &&...)

Updates the value of an existing bucket ACL.

Note: For changing BucketAccessControl, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    gcs::BucketAccessControl desired_acl =
        gcs::BucketAccessControl().set_entity(entity).set_role(role);

    StatusOr<gcs::BucketAccessControl> updated_acl =
        client.UpdateBucketAcl(bucket_name, desired_acl);

    if (!updated_acl) throw std::move(updated_acl).status();
    std::cout << "Bucket ACL updated. The ACL entry for "
              << updated_acl->entity() << " in bucket " << updated_acl->bucket()
              << " is " << *updated_acl << "\n";
  }

PatchBucketAcl(std::string const &, std::string const &, BucketAccessControl const &, BucketAccessControl const &, Options &&...)

Patches the value of an existing bucket ACL.

Computes the delta between a previous value for an BucketAccessControl and the new value for an BucketAccessControl and apply that delta.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::BucketAccessControl> original_acl =
        client.GetBucketAcl(bucket_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    auto new_acl = *original_acl;
    new_acl.set_role(role);

    StatusOr<gcs::BucketAccessControl> patched_acl =
        client.PatchBucketAcl(bucket_name, entity, *original_acl, new_acl);

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in bucket "
              << patched_acl->bucket() << " is now " << *patched_acl << "\n";
  }

PatchBucketAcl(std::string const &, std::string const &, BucketAccessControlPatchBuilder const &, Options &&...)

Patches the value of an existing bucket ACL.

This API allows the application to patch an BucketAccessControl without having to read the current value.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::BucketAccessControl> patched_acl = client.PatchBucketAcl(
        bucket_name, entity,
        gcs::BucketAccessControlPatchBuilder().set_role(role));

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in bucket "
              << patched_acl->bucket() << " is now " << *patched_acl << "\n";
  }

ListObjectAcl(std::string const &, std::string const &, Options &&...)

Retrieves the list of ObjectAccessControl items for an object.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    StatusOr<std::vector<gcs::ObjectAccessControl>> items =
        client.ListObjectAcl(bucket_name, object_name);

    if (!items) throw std::move(items).status();
    std::cout << "ACLs for object=" << object_name << " in bucket "
              << bucket_name << "\n";
    for (gcs::ObjectAccessControl const& acl : *items) {
      std::cout << acl.role() << ":" << acl.entity() << "\n";
    }
  }

Parameters
Name	Description
`bucket_name`	`std::string const &` the name of the bucket that contains the object.
`object_name`	`std::string const &` the name of the object to be deleted.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `Generation`, and `UserProject`.
`typename...`

Returns
Type	Description
`StatusOr< std::vector< ObjectAccessControl > >`

CreateObjectAcl(std::string const &, std::string const &, std::string const &, std::string const &, Options &&...)

Creates a new entry in the object ACL.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> object_acl =
        client.CreateObjectAcl(bucket_name, object_name, entity, role);

    if (!object_acl) throw std::move(object_acl).status();
    std::cout << "Role " << object_acl->role() << " granted to "
              << object_acl->entity() << " on " << object_acl->object()
              << "\nFull attributes: " << *object_acl << "\n";
  }

DeleteObjectAcl(std::string const &, std::string const &, std::string const &, Options &&...)

Deletes one access control entry in one object.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity) {
    google::cloud::Status status =
        client.DeleteObjectAcl(bucket_name, object_name, entity);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted ACL entry for " << entity << " in object "
              << object_name << " in bucket " << bucket_name << "\n";
  }

GetObjectAcl(std::string const &, std::string const &, std::string const &, Options &&...)

Gets the value of an existing object ACL.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity) {
    StatusOr<gcs::ObjectAccessControl> acl =
        client.GetObjectAcl(bucket_name, object_name, entity);

    if (!acl) throw std::move(acl).status();
    std::cout << "ACL entry for " << acl->entity() << " in object "
              << acl->object() << " in bucket " << acl->bucket() << " is "
              << *acl << "\n";
  }

UpdateObjectAcl(std::string const &, std::string const &, ObjectAccessControl const &, Options &&...)

Updates the value of an existing object ACL.

Note: For changing ObjectAccessControl, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> current_acl =
        client.GetObjectAcl(bucket_name, object_name, entity);

    if (!current_acl) throw std::move(current_acl).status();
    current_acl->set_role(role);

    StatusOr<gcs::ObjectAccessControl> updated_acl =
        client.UpdateObjectAcl(bucket_name, object_name, *current_acl);

    if (!updated_acl) throw std::move(updated_acl).status();
    std::cout << "ACL entry for " << updated_acl->entity() << " in object "
              << updated_acl->object() << " in bucket " << updated_acl->bucket()
              << " is now " << *updated_acl << "\n";
  }

PatchObjectAcl(std::string const &, std::string const &, std::string const &, ObjectAccessControl const &, ObjectAccessControl const &, Options &&...)

Patches the value of an existing object ACL.

Compute the delta between a previous value for an ObjectAccessControl and the new value for an ObjectAccessControl and apply that delta.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> original_acl =
        client.GetObjectAcl(bucket_name, object_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    gcs::ObjectAccessControl new_acl = *original_acl;
    new_acl.set_role(role);

    StatusOr<gcs::ObjectAccessControl> patched_acl = client.PatchObjectAcl(
        bucket_name, object_name, entity, *original_acl, new_acl);

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in object "
              << patched_acl->object() << " in bucket " << patched_acl->bucket()
              << " is now " << *patched_acl << "\n";
  }

PatchObjectAcl(std::string const &, std::string const &, std::string const &, ObjectAccessControlPatchBuilder const &, Options &&...)

Patches the value of an existing object ACL.

This API allows the application to patch an ObjectAccessControl without having to read the current value.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> patched_acl = client.PatchObjectAcl(
        bucket_name, object_name, entity,
        gcs::ObjectAccessControlPatchBuilder().set_role(role));

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in object "
              << patched_acl->object() << " in bucket " << patched_acl->bucket()
              << " is now " << *patched_acl << "\n";
  }

ListDefaultObjectAcl(std::string const &, Options &&...)

Retrieves the default object ACL for a bucket as a vector of ObjectAccessControl items.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<std::vector<gcs::ObjectAccessControl>> items =
        client.ListDefaultObjectAcl(bucket_name);

    if (!items) throw std::move(items).status();
    std::cout << "ACLs for bucket=" << bucket_name << "\n";
    for (gcs::ObjectAccessControl const& acl : *items) {
      std::cout << acl.role() << ":" << acl.entity() << "\n";
    }
  }

CreateDefaultObjectAcl(std::string const &, std::string const &, std::string const &, Options &&...)

Creates a new entry in the default object ACL for a bucket.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> default_object_acl =
        client.CreateDefaultObjectAcl(bucket_name, entity, role);
    if (!default_object_acl) throw std::move(default_object_acl).status();

    std::cout << "Role " << default_object_acl->role()
              << " will be granted default to " << default_object_acl->entity()
              << " on any new object created on bucket "
              << default_object_acl->bucket() << "\n"
              << "Full attributes: " << *default_object_acl << "\n";
  }

DeleteDefaultObjectAcl(std::string const &, std::string const &, Options &&...)

Deletes an entry from the default object ACL in a bucket.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    google::cloud::Status status =
        client.DeleteDefaultObjectAcl(bucket_name, entity);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted ACL entry for " << entity << " in bucket "
              << bucket_name << "\n";
  }

GetDefaultObjectAcl(std::string const &, std::string const &, Options &&...)

Gets the value of a default object ACL in a bucket.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    StatusOr<gcs::ObjectAccessControl> acl =
        client.GetDefaultObjectAcl(bucket_name, entity);

    if (!acl) throw std::move(acl).status();
    std::cout << "Default Object ACL entry for " << acl->entity()
              << " in bucket " << acl->bucket() << " is " << *acl << "\n";
  }

UpdateDefaultObjectAcl(std::string const &, ObjectAccessControl const &, Options &&...)

Updates the value of an existing default object ACL.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Note: For changing default object access controls, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> original_acl =
        client.GetDefaultObjectAcl(bucket_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    original_acl->set_role(role);

    StatusOr<gcs::ObjectAccessControl> updated_acl =
        client.UpdateDefaultObjectAcl(bucket_name, *original_acl);
    if (!updated_acl) throw std::move(updated_acl).status();

    std::cout << "Default Object ACL entry for " << updated_acl->entity()
              << " in bucket " << updated_acl->bucket() << " is now "
              << *updated_acl << "\n";
  }

PatchDefaultObjectAcl(std::string const &, std::string const &, ObjectAccessControl const &, ObjectAccessControl const &, Options &&...)

Patches the value of an existing default object ACL.

Compute the delta between a previous and new values for a default object access control, and apply that delta.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> original_acl =
        client.GetDefaultObjectAcl(bucket_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    auto new_acl = *original_acl;
    new_acl.set_role(role);

    StatusOr<gcs::ObjectAccessControl> patched_acl =
        client.PatchDefaultObjectAcl(bucket_name, entity, *original_acl,
                                     new_acl);

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "Default Object ACL entry for " << patched_acl->entity()
              << " in bucket " << patched_acl->bucket() << " is now "
              << *patched_acl << "\n";
  }

PatchDefaultObjectAcl(std::string const &, std::string const &, ObjectAccessControlPatchBuilder const &, Options &&...)

Patches the value of an existing default object ACL.

This API allows the application to patch an ObjectAccessControl without having to read the current value.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> patched_acl =
        client.PatchDefaultObjectAcl(
            bucket_name, entity,
            gcs::ObjectAccessControlPatchBuilder().set_role(role));

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "Default Object ACL entry for " << patched_acl->entity()
              << " in bucket " << patched_acl->bucket() << " is now "
              << *patched_acl << "\n";
  }

GetServiceAccountForProject(std::string const &, Options &&...)

Gets the GCS service account for a given project.

A service account is a special Google account that belongs to your application, virtual machine, or to a Google service when acting on your behalf. This API allows you to discover the GCS service account for the project_id project.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& project_id) {
    StatusOr<gcs::ServiceAccount> account =
        client.GetServiceAccountForProject(project_id);
    if (!account) throw std::move(account).status();

    std::cout << "The service account details for project " << project_id
              << " are " << *account << "\n";
  }

GetServiceAccount(Options &&...)

Gets the GCS service account for the default project.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

Any parameters of type OverrideDefaultProject, with a value.
Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client) {
    StatusOr<gcs::ServiceAccount> account = client.GetServiceAccount();
    if (!account) throw std::move(account).status();

    std::cout << "The service account details are " << *account << "\n";
  }

ListHmacKeys(Options &&...)

List the available HMAC keys.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

Any parameters of type OverrideDefaultProject, with a value.
Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client) {
    int count = 0;
    gcs::ListHmacKeysReader hmac_keys_list = client.ListHmacKeys();
    for (auto& key : hmac_keys_list) {
      if (!key) throw std::move(key).status();

      std::cout << "service_account_email = " << key->service_account_email()
                << "\naccess_id = " << key->access_id() << "\n";
      ++count;
    }
    if (count == 0) {
      std::cout << "No HMAC keys in default project\n";
    }
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& service_account) {
    int count = 0;
    gcs::ListHmacKeysReader hmac_keys_list =
        client.ListHmacKeys(gcs::ServiceAccountFilter(service_account));
    for (auto& key : hmac_keys_list) {
      if (!key) throw std::move(key).status();

      std::cout << "service_account_email = " << key->service_account_email()
                << "\naccess_id = " << key->access_id() << "\n";
      ++count;
    }
    if (count == 0) {
      std::cout << "No HMAC keys for service account " << service_account
                << " in default project\n";
    }
  }

CreateHmacKey(std::string, Options &&...)

Create a new HMAC key.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

Any parameters of type OverrideDefaultProject, with a value.
Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This operation is not idempotent. Retrying the operation will create a new key each time.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  return [](gcs::Client client, std::string const& service_account_email) {
    StatusOr<std::pair<gcs::HmacKeyMetadata, std::string>> key_info =
        client.CreateHmacKey(service_account_email);
    if (!key_info) throw std::move(key_info).status();

    std::cout << "The base64 encoded secret is: " << key_info->second
              << "\nDo not miss that secret, there is no API to recover it."
              << "\nThe HMAC key metadata is: " << key_info->first << "\n";
    return key_info->first.access_id();
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  return [](gcs::Client client, std::string const& project_id,
            std::string const& service_account_email) {
    StatusOr<std::pair<gcs::HmacKeyMetadata, std::string>> hmac_key_details =
        client.CreateHmacKey(service_account_email,
                             gcs::OverrideDefaultProject(project_id));
    if (!hmac_key_details) throw std::move(hmac_key_details).status();

    std::cout << "The base64 encoded secret is: " << hmac_key_details->second
              << "\nDo not miss that secret, there is no API to recover it."
              << "\nThe HMAC key metadata is: " << hmac_key_details->first
              << "\n";
    return hmac_key_details->first.access_id();
  }

DeleteHmacKey(std::string, Options &&...)

Delete a HMAC key in the default project.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

Any parameters of type OverrideDefaultProject, with a value.
Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This operation is always idempotent. An access id identifies a single HMAC key, calling the operation multiple times can succeed only once.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& access_id) {
    google::cloud::Status status = client.DeleteHmacKey(access_id);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "The key is deleted, though it may still appear"
              << " in ListHmacKeys() results.\n";
  }

GetHmacKey(std::string, Options &&...)

Get an existing HMAC key in the default project.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

Any parameters of type OverrideDefaultProject, with a value.
Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This is a read-only operation and therefore it is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& access_id) {
    StatusOr<gcs::HmacKeyMetadata> hmac_key = client.GetHmacKey(access_id);
    if (!hmac_key) throw std::move(hmac_key).status();

    std::cout << "The HMAC key metadata is: " << *hmac_key << "\n";
  }

UpdateHmacKey(std::string, HmacKeyMetadata, Options &&...)

Update an existing HMAC key in the default project.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

Any parameters of type OverrideDefaultProject, with a value.
Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This operation is only idempotent if the etag attribute in resource is set, or if the IfMatchEtag option is set.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& access_id,
     std::string const& state) {
    StatusOr<gcs::HmacKeyMetadata> updated = client.UpdateHmacKey(
        access_id, gcs::HmacKeyMetadata().set_state(state));
    if (!updated) throw std::move(updated).status();

    std::cout << "The updated HMAC key metadata is: " << *updated << "\n";
  }

CreateV2SignedUrl(std::string, std::string, std::string, Options &&...)

Create a V2 signed URL for the given parameters.

Helper Functions

The following functions create a AddSubResourceOption with less opportunities for typos in the sub-resource name: WithAcl(), WithBilling(), WithCompose(), WithCors(), WithEncryption(), WithEncryptionConfig(), WithLifecycle(), WithLocation(), WithLogging(), WithStorageClass(), and WithTagging().

Likewise, the following helper functions can create properly formatted AddExtensionHeaderOption objects: WithGeneration(), WithGenerationMarker(), WithMarker(), WithResponseContentDisposition(), WithResponseContentType(), and WithUserProject().

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV2SignedUrl(
        "GET", bucket_name, object_name,
        gcs::ExpirationTime(std::chrono::system_clock::now() +
                            std::chrono::minutes(15)),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl '" << *signed_url << "'\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV2SignedUrl(
        "PUT", bucket_name, object_name,
        gcs::ExpirationTime(std::chrono::system_clock::now() +
                            std::chrono::minutes(15)),
        gcs::ContentType("application/octet-stream"),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl -X PUT -H 'Content-Type: application/octet-stream'"
              << " --upload-file my-file '" << *signed_url << "'\n";
  }

CreateV4SignedUrl(std::string, std::string, std::string, Options &&...)

Create a V4 signed URL for the given parameters.

Helper Functions

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV4SignedUrl(
        "GET", bucket_name, object_name,
        gcs::SignedUrlDuration(std::chrono::minutes(15)),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl '" << *signed_url << "'\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV4SignedUrl(
        "PUT", bucket_name, object_name,
        gcs::SignedUrlDuration(std::chrono::minutes(15)),
        gcs::AddExtensionHeader("content-type", "application/octet-stream"),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl -X PUT -H 'Content-Type: application/octet-stream'"
              << " --upload-file my-file '" << *signed_url << "'\n";
  }

ListNotifications(std::string const &, Options &&...)

Retrieves the list of Notifications for a Bucket.

Cloud Pub/Sub Notifications sends information about changes to objects in your buckets to Google Cloud Pub/Sub service.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<std::vector<gcs::NotificationMetadata>> items =
        client.ListNotifications(bucket_name);
    if (!items) throw std::move(items).status();

    std::cout << "Notifications for bucket=" << bucket_name << "\n";
    for (gcs::NotificationMetadata const& notification : *items) {
      std::cout << notification << "\n";
    }
  }

Parameters
Name	Description
`bucket_name`	`std::string const &` the name of the bucket.
`options`	`Options &&...` a list of optional query parameters and/or request headers. Valid types for this operation include `UserProject`.
`typename...`

Returns
Type	Description
`StatusOr< std::vector< NotificationMetadata > >`

CreateNotification(std::string const &, std::string const &, NotificationMetadata, Options &&...)

Creates a new notification config for a Bucket.

Cloud Pub/Sub Notifications send information about changes to objects in your buckets to Google Cloud Pub/Sub service. You can create multiple notifications per Bucket, with different topics and filtering options.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& topic_name) {
    StatusOr<gcs::NotificationMetadata> notification =
        client.CreateNotification(bucket_name, topic_name,
                                  gcs::NotificationMetadata());
    if (!notification) throw std::move(notification).status();

    std::cout << "Successfully created notification " << notification->id()
              << " for bucket " << bucket_name << "\n";
    std::cout << "Full details for the notification:\n"
              << *notification << "\n";
  }

CreateNotification(std::string const &, std::string const &, std::string const &, NotificationMetadata, Options &&...)

Creates a new notification config for a Bucket.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& topic_name) {
    StatusOr<gcs::NotificationMetadata> notification =
        client.CreateNotification(bucket_name, topic_name,
                                  gcs::NotificationMetadata());
    if (!notification) throw std::move(notification).status();

    std::cout << "Successfully created notification " << notification->id()
              << " for bucket " << bucket_name << "\n";
    std::cout << "Full details for the notification:\n"
              << *notification << "\n";
  }

GetNotification(std::string const &, std::string const &, Options &&...)

Gets the details about a notification config in a given Bucket.

Cloud Pub/Sub Notifications sends information about changes to objects in your buckets to Google Cloud Pub/Sub service. You can create multiple notifications per Bucket, with different topics and filtering options. This function fetches the detailed information for a given notification config.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& notification_id) {
    StatusOr<gcs::NotificationMetadata> notification =
        client.GetNotification(bucket_name, notification_id);
    if (!notification) throw std::move(notification).status();

    std::cout << "Notification " << notification->id() << " for bucket "
              << bucket_name << "\n";
    if (notification->object_name_prefix().empty()) {
      std::cout << "This notification is sent for all objects in the bucket\n";
    } else {
      std::cout << "This notification is sent only for objects starting with"
                << " the prefix " << notification->object_name_prefix() << "\n";
    }
    std::cout << "Full details for the notification:\n"
              << *notification << "\n";
  }

DeleteNotification(std::string const &, std::string const &, Options &&...)

Delete an existing notification config in a given Bucket.

Idempotency

This operation is always idempotent because it only acts on a specific notification_id, the state after calling this function multiple times is to delete that notification. New notifications get different ids.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& notification_id) {
    google::cloud::Status status =
        client.DeleteNotification(bucket_name, notification_id);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "Successfully deleted notification " << notification_id
              << " on bucket " << bucket_name << "\n";
  }

CreateSignedPolicyDocument(PolicyDocument, Options &&...)

Create a signed policy document.

Note: The application must ensure that any document created with this function contains valid conditions. This function does not do any error checking, e.g. that a ExactMatchObject() condition contains two elements. Using the provided helper functions can prevent errors.

Helper Functions

The following functions create a PolicyDocumentCondition with less opportunities for typos: StartsWith(), ExactMatchObject(), ExactMatch(), ContentLengthRange().

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& signing_account) {
    StatusOr<gcs::PolicyDocumentResult> document =
        client.CreateSignedPolicyDocument(
            gcs::PolicyDocument{
                std::chrono::system_clock::now() + std::chrono::minutes(15),
                {
                    gcs::PolicyDocumentCondition::StartsWith("key", ""),
                    gcs::PolicyDocumentCondition::ExactMatchObject(
                        "acl", "bucket-owner-read"),
                    gcs::PolicyDocumentCondition::ExactMatchObject("bucket",
                                                                   bucket_name),
                    gcs::PolicyDocumentCondition::ExactMatch("Content-Type",
                                                             "image/jpeg"),
                    gcs::PolicyDocumentCondition::ContentLengthRange(0,
                                                                     1000000),
                }},
            gcs::SigningAccount(signing_account));
    if (!document) throw std::move(document).status();

    std::cout << "The signed document is: " << *document << "\n\n"
              << "You can use this with an HTML form.\n";
  }

GenerateSignedPostPolicyV4(PolicyDocumentV4, Options &&...)

Create a signed V4 policy document.

Helper Functions

The following functions create a PolicyDocumentCondition with less opportunities for typos: StartsWith(), ExactMatchObject(), ExactMatch(), ContentLengthRange().

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& signing_account) {
    StatusOr<gcs::PolicyDocumentV4Result> document =
        client.GenerateSignedPostPolicyV4(
            gcs::PolicyDocumentV4{
                bucket_name,
                "scan_0001.jpg",
                std::chrono::minutes(15),
                std::chrono::system_clock::now(),
                {
                    gcs::PolicyDocumentCondition::StartsWith("key", ""),
                    gcs::PolicyDocumentCondition::ExactMatchObject(
                        "acl", "bucket-owner-read"),
                    gcs::PolicyDocumentCondition::ExactMatch("Content-Type",
                                                             "image/jpeg"),
                    gcs::PolicyDocumentCondition::ContentLengthRange(0,
                                                                     1000000),
                }},
            gcs::SigningAccount(signing_account));
    if (!document) throw std::move(document).status();

    std::cout << "The signed document is: " << *document << "\n\n"
              << "You can use this with an HTML form.\n";
  }

raw_client() const

Access the underlying StorageConnection.

Returns
Type	Description
`std::shared_ptr< internal::StorageConnection >`

static CreateDefaultClient()

Create a Client using ClientOptions::CreateDefaultClientOptions().

Returns
Type	Description
`StatusOr< Client >`

Returns
Type	Description
`ListHmacKeysReader`	A range to iterate over the available HMAC keys.

Parameters
Name	Description
`service_account`	`std::string` the service account email where you want to create the new HMAC key.
`options`	`Options &&...` a list of optional query parameters and/or request headers. In addition to the options common to all requests, this operation accepts `OverrideDefaultProject`.
`typename...`

Returns
Type	Description
`StatusOr< std::pair< HmacKeyMetadata, std::string > >`	This operation returns the new HMAC key metadata and the HMAC key secret (encoded as a base64 string). This is the only request that returns the secret.

Parameters
Name	Description
`access_id`	`std::string` the HMAC key `access_id()` that you want to delete. Each HMAC key is assigned an `access_id()` attribute at creation time.
`options`	`Options &&...` a list of optional query parameters and/or request headers. In addition to the options common to all requests, this operation accepts `OverrideDefaultProject`.
`typename...`

Returns
Type	Description
`StatusOr< HmacKeyMetadata >`	This operation returns the new HMAC key metadata.

Parameters
Name	Description
`verb`	`std::string` the operation allowed through this signed URL, `GET`, `POST`, `PUT`, `HEAD`, etc. are valid values.
`bucket_name`	`std::string` the name of the bucket.
`object_name`	`std::string` the name of the object, note that the object may not exist for signed URLs that upload new objects. Use an empty string for requests that only affect a bucket.
`options`	`Options &&...` a list of optional parameters for the signed URL, this include: `ExpirationTime`, `MD5HashValue`, `ContentType`, `SigningAccount`, `SigningAccountDelegates`, `AddExtensionHeaderOption`, `AddQueryParameterOption`, and `AddSubResourceOption`. Note that only the last `AddSubResourceOption` option has any effect.
`typename...`

Returns
Type	Description
`StatusOr< std::string >`	the signed URL.

Parameters
Name	Description
`document`	`PolicyDocument` the policy document.
`options`	`Options &&...` a list of optional parameters, this includes: `SigningAccount`, and `SigningAccountDelegates`.
`typename...`

Class Client (2.18.0)

Performance

Connection Pool

Thread-safety

Credentials

Error Handling

Optional Request Options

Per-operation Overrides

Retry, Backoff, and Idempotency Policies

See Also

See Also

See Also

See Also

See Also

See Also

See Also

See Also

Constructors

Client(Options)

See Also

Idempotency Policy Example

Modified Retry Policy Example

Change Credentials Example

Client(ClientOptions, Policies &&...)

Client(std::shared_ptr< oauth2::Credentials >, Policies &&...)

Client(std::shared_ptr< internal::StorageConnection > const &, Policies &&...)

Client(std::shared_ptr< internal::StorageConnection >, NoDecorations)

Functions

ListBucketsForProject(std::string const &, Options &&...)

Idempotency

Example

ListBuckets(Options &&...)

Idempotency

Example

CreateBucket(std::string, BucketMetadata, Options &&...)

Idempotency

Example

See Also

CreateBucketForProject(std::string, std::string, BucketMetadata, Options &&...)

Idempotency

Example

See Also

GetBucketMetadata(std::string const &, Options &&...)

Idempotency

Example

DeleteBucket(std::string const &, Options &&...)

Idempotency

Example

UpdateBucket(std::string, BucketMetadata, Options &&...)

Idempotency

Example

See Also

PatchBucket(std::string, BucketMetadata const &, BucketMetadata const &, Options &&...)

Idempotency

Example

See Also

PatchBucket(std::string, BucketMetadataPatchBuilder const &, Options &&...)

Idempotency

Example

See Also

GetNativeBucketIamPolicy(std::string const &, Options &&...)

Idempotency

Example

See Also

SetNativeBucketIamPolicy(std::string const &, NativeIamPolicy const &, Options &&...)

Idempotency

Example: adding a new member

Example: removing a IAM member

See Also

TestBucketIamPermissions(std::string, std::vector< std::string >, Options &&...)

Idempotency

Example

LockBucketRetentionPolicy(std::string const &, std::uint64_t, Options &&...)

Idempotency

Example: lock the retention policy

Example: get the current retention policy

Example: set the current retention policy

Example: remove the retention policy

See Also

See Also