Class CollectionReference (2.9.0)

CollectionReference(*path, **kwargs)

A reference to a collection in a Firestore database.

The collection may already exist or this class can facilitate creation of documents within the collection.

Parameters

Name	Description
`path`	`Tuple[str, ...]` The components in the collection path. This is a series of strings representing each collection and sub-collection ID, as well as the document IDs for any documents that contain a sub-collection.
`kwargs`	`dict` The keyword arguments for the constructor. The only supported keyword is `client` and it must be a Client if provided. It represents the client that created this collection reference.

Methods

add

add(document_data: dict, document_id: Optional[str] = None, retry: google.api_core.retry.Retry = <_MethodDefault._DEFAULT_VALUE: <object object>>, timeout: Optional[float] = None)

Create a document in the Firestore database with the provided data.

Parameters

Name	Description
`document_data`	`dict` Property names and values to use for creating the document.
`document_id`	`Optional[str]` The document identifier within the current collection. If not provided, an ID will be automatically assigned by the server (the assigned ID will be a random 20 character string composed of digits, uppercase and lowercase letters).
`retry`	`google.api_core.retry.Retry` Designation of what errors, if any, should be retried. Defaults to a system-specified policy.
`timeout`	`float` The timeout for this request. Defaults to a system-specified value.

Exceptions

Type	Description
`google.cloud.exceptions.Conflict`	If `document_id` is provided and the document already exists.

Returns

Type	Description
`Tuple[google.protobuf.timestamp_pb2.Timestamp, DocumentReference]`	Pair of * The `update_time` when the document was created/overwritten. * A document reference for the created document.

get

get(transaction: Optional[google.cloud.firestore_v1.transaction.Transaction] = None, retry: google.api_core.retry.Retry = <_MethodDefault._DEFAULT_VALUE: <object object>>, timeout: Optional[float] = None)

Read the documents in this collection.

This sends a RunQuery RPC and returns a list of documents returned in the stream of RunQueryResponse messages.

Parameters

Name	Description
`retry`	`google.api_core.retry.Retry` Designation of what errors, if any, should be retried. Defaults to a system-specified policy.
`timeout`	`float If a transaction is used and it already has write operations added, this method cannot be used (i.e. read-after-write is not allowed).` The timeout for this request. Defaults to a system-specified value.

Returns

Type	Description
`list`	The documents in this collection that match the query.

list_documents

list_documents(page_size: Optional[int] = None, retry: google.api_core.retry.Retry = <_MethodDefault._DEFAULT_VALUE: <object object>>, timeout: Optional[float] = None)

List all subdocuments of the current collection.

Parameters

Name	Description
`page_size`	`Optional[int]]` The maximum number of documents in each page of results from this request. Non-positive values are ignored. Defaults to a sensible value set by the API.
`retry`	`google.api_core.retry.Retry` Designation of what errors, if any, should be retried. Defaults to a system-specified policy.
`timeout`	`float` The timeout for this request. Defaults to a system-specified value.

Returns

Type	Description
`Sequence[DocumentReference]`	iterator of subdocuments of the current collection. If the collection does not exist at the time of `snapshot`, the iterator will be empty

on_snapshot

on_snapshot(callback: Callable)

Monitor the documents in this collection.

This starts a watch on this collection using a background thread. The provided callback is run on the snapshot of the documents.

Parameter

Name Description

callback

Callable[[CollectionSnapshot], NoneType] .. rubric:: Example from google.cloud import firestore_v1 db = firestore_v1.Client() collection_ref = db.collection(u'users') def on_snapshot(collection_snapshot, changes, read_time): for doc in collection_snapshot.documents: print(u'{} => {}'.format(doc.id, doc.to_dict())) # Watch this collection collection_watch = collection_ref.on_snapshot(on_snapshot) # Terminate this watch collection_watch.unsubscribe()

a callback to run when a change occurs.

stream

stream(transaction: Optional[google.cloud.firestore_v1.transaction.Transaction] = None, retry: google.api_core.retry.Retry = <_MethodDefault._DEFAULT_VALUE: <object object>>, timeout: Optional[float] = None)

Read the documents in this collection.

This sends a RunQuery RPC and then returns an iterator which consumes each document returned in the stream of RunQueryResponse messages.

Note: The underlying stream of responses will time out after the max_rpc_timeout_millis value set in the GAPIC client configuration for the RunQuery API. Snapshots not consumed from the iterator before that point will be lost.

Parameters

Name	Description
`transaction`	`Optional[ Transaction]` An existing transaction that the query will run in.
`retry`	`google.api_core.retry.Retry` Designation of what errors, if any, should be retried. Defaults to a system-specified policy.
`timeout`	`float :Yields: DocumentSnapshot -- The next document that fulfills the query.` The timeout for this request. Defaults to a system-specified value.