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[[["Leicht verständlich","easyToUnderstand","thumb-up"],["Mein Problem wurde gelöst","solvedMyProblem","thumb-up"],["Sonstiges","otherUp","thumb-up"]],[["Schwer verständlich","hardToUnderstand","thumb-down"],["Informationen oder Beispielcode falsch","incorrectInformationOrSampleCode","thumb-down"],["Benötigte Informationen/Beispiele nicht gefunden","missingTheInformationSamplesINeed","thumb-down"],["Problem mit der Übersetzung","translationIssue","thumb-down"],["Sonstiges","otherDown","thumb-down"]],[],[[["\u003cp\u003eThis content demonstrates how to use transactions in Google Cloud Datastore to either retrieve an existing entity or create a new one if it doesn't exist.\u003c/p\u003e\n"],["\u003cp\u003eCode samples are provided in C#, Go, Java, Node.js, PHP, Python, and Ruby, illustrating the process of getting or creating an entity within a transaction.\u003c/p\u003e\n"],["\u003cp\u003eThe examples show how to look up an entity using its key and how to insert or save the entity into the database using the \u003ccode\u003etransaction\u003c/code\u003e class functions.\u003c/p\u003e\n"],["\u003cp\u003eThe content links to the documentation for Cloud Datastore transactions, as well as instructions for setting up client libraries and authentication.\u003c/p\u003e\n"],["\u003cp\u003eThe page also provides links to the specific API reference documentation for each of the languages showcased in the samples.\u003c/p\u003e\n"]]],[],null,["# Get or create in a transaction.\n\nExplore further\n---------------\n\n\nFor detailed documentation that includes this code sample, see the following:\n\n- [Cloud Datastore Transactions](/datastore/docs/concepts/cloud-datastore-transactions)\n- [Transactions](/datastore/docs/concepts/transactions)\n\nCode sample\n-----------\n\n### C#\n\n\nTo learn how to install and use the client library for Datastore mode, see\n[Datastore mode client libraries](/datastore/docs/reference/libraries).\n\n\nFor more information, see the\n[Datastore mode C# API\nreference documentation](https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Datastore.V1/latest).\n\n\nTo authenticate to Datastore mode, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n Entity task;\n using (var transaction = _db.BeginTransaction())\n {\n task = transaction.Lookup(_sampleTask.Key);\n if (task == null)\n {\n transaction.Insert(_sampleTask);\n transaction.Commit();\n }\n }\n\n### Go\n\n\nTo learn how to install and use the client library for Datastore mode, see\n[Datastore mode client libraries](/datastore/docs/reference/libraries).\n\n\nFor more information, see the\n[Datastore mode Go API\nreference documentation](https://cloud.google.com/go/docs/reference/cloud.google.com/go/datastore/latest).\n\n\nTo authenticate to Datastore mode, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n _, err := client.RunInTransaction(ctx, func(tx *datastore.Transaction) error {\n \tvar task Task\n \tif err := tx.Get(key, &task); err != datastore.ErrNoSuchEntity {\n \t\treturn err\n \t}\n \t_, err := tx.Put(key, &Task{\n \t\tCategory: \"Personal\",\n \t\tDone: false,\n \t\tPriority: 4,\n \t\tDescription: \"Learn Cloud Datastore\",\n \t})\n \treturn err\n })\n\n### Java\n\n\nTo learn how to install and use the client library for Datastore mode, see\n[Datastore mode client libraries](/datastore/docs/reference/libraries).\n\n\nFor more information, see the\n[Datastore mode Java API\nreference documentation](https://cloud.google.com/java/docs/reference/google-cloud-datastore/latest/history).\n\n\nTo authenticate to Datastore mode, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n Entity task;\n Transaction txn = datastore.newTransaction();\n try {\n task = txn.get(taskKey);\n if (task == null) {\n task = Entity.newBuilder(taskKey).build();\n txn.put(task);\n txn.commit();\n }\n } finally {\n if (txn.isActive()) {\n txn.rollback();\n }\n }\n\n### Node.js\n\n\nTo learn how to install and use the client library for Datastore mode, see\n[Datastore mode client libraries](/datastore/docs/reference/libraries).\n\n\nFor more information, see the\n[Datastore mode Node.js API\nreference documentation](https://cloud.google.com/nodejs/docs/reference/datastore/latest).\n\n\nTo authenticate to Datastore mode, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n async function getOrCreate(taskKey, taskData) {\n const taskEntity = {\n key: taskKey,\n data: taskData,\n };\n const transaction = datastore.transaction();\n\n try {\n await transaction.run();\n const [task] = await transaction.get(taskKey);\n if (task) {\n // The task entity already exists.\n await transaction.rollback();\n } else {\n // Create the task entity.\n transaction.save(taskEntity);\n await transaction.commit();\n }\n return taskEntity;\n } catch (err) {\n await transaction.rollback();\n }\n }\n\n### PHP\n\n\nTo learn how to install and use the client library for Datastore mode, see\n[Datastore mode client libraries](/datastore/docs/reference/libraries).\n\n\nFor more information, see the\n[Datastore mode PHP API\nreference documentation](https://googleapis.github.io/google-cloud-php/#/docs/cloud-datastore/latest).\n\n\nTo authenticate to Datastore mode, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n $transaction = $datastore-\u003etransaction();\n $entity = $transaction-\u003elookup($task-\u003ekey());\n if ($entity === null) {\n $entity = $transaction-\u003einsert($task);\n $transaction-\u003ecommit();\n }\n\n### Python\n\n\nTo learn how to install and use the client library for Datastore mode, see\n[Datastore mode client libraries](/datastore/docs/reference/libraries).\n\n\nFor more information, see the\n[Datastore mode Python API\nreference documentation](https://cloud.google.com/python/docs/reference/datastore/latest).\n\n\nTo authenticate to Datastore mode, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n from google.cloud import https://cloud.google.com/python/docs/reference/datastore/latest/\n\n # For help authenticating your client, visit\n # https://cloud.google.com/docs/authentication/getting-started\n client = https://cloud.google.com/python/docs/reference/datastore/latest/.https://cloud.google.com/python/docs/reference/datastore/latest/google.cloud.datastore.client.Client.html()\n\n import datetime\n\n with client.https://cloud.google.com/python/docs/reference/datastore/latest/google.cloud.datastore.client.Client.html#google_cloud_datastore_client_Client_transaction():\n key = client.https://cloud.google.com/python/docs/reference/datastore/latest/google.cloud.datastore.client.Client.html#google_cloud_datastore_client_Client_key(\n \"Task\", datetime.datetime.now(tz=datetime.timezone.utc).isoformat()\n )\n\n task = client.https://cloud.google.com/python/docs/reference/datastore/latest/google.cloud.datastore.client.Client.html#google_cloud_datastore_client_Client_get(key)\n\n if not task:\n task = https://cloud.google.com/python/docs/reference/datastore/latest/.https://cloud.google.com/python/docs/reference/datastore/latest/google.cloud.datastore.entity.Entity.html(key)\n task.update({\"description\": \"Example task\"})\n client.https://cloud.google.com/python/docs/reference/datastore/latest/google.cloud.datastore.client.Client.html#google_cloud_datastore_client_Client_put(task)\n\n return task\n\n### Ruby\n\n\nTo learn how to install and use the client library for Datastore mode, see\n[Datastore mode client libraries](/datastore/docs/reference/libraries).\n\n\nFor more information, see the\n[Datastore mode Ruby API\nreference documentation](/ruby/docs/reference/google-cloud-datastore/latest).\n\n\nTo authenticate to Datastore mode, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n task = nil\n datastore.transaction do |tx|\n task = tx.find task_key\n if task.nil?\n task = datastore.entity task_key do |t|\n t[\"category\"] = \"Personal\"\n t[\"done\"] = false\n t[\"priority\"] = 4\n t[\"description\"] = \"Learn Cloud Datastore\"\n end\n tx.save task\n end\n end\n\nWhat's next\n-----------\n\n\nTo search and filter code samples for other Google Cloud products, see the\n[Google Cloud sample browser](/docs/samples?product=datastore)."]]