def on_snapshot(self, callback):
"""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.
Args:
callback(~.firestore.collection.CollectionSnapshot): a callback
to run when a change occurs.
Example:
from google.cloud import firestore
db = firestore.Client()
collection_ref = db.collection(u'users')
def on_snapshot(collection_snapshot):
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()
"""
return Watch.for_query(
query_mod.Query(self),
callback,
document.DocumentSnapshot,
document.DocumentReference,
)
def get(self, transaction=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.
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).
Args:
transaction (Optional[~.firestore_v1beta1.transaction.\
Transaction]): An existing transaction that the query will
run in.
Yields:
~.firestore_v1beta1.document.DocumentSnapshot: The next
document that fulfills the query.
"""
query = query_mod.Query(self)
return query.get(transaction=transaction)
def limit(self, count):
"""Create a limited query with this collection as parent.
See
:meth:`~.firestore_v1beta1.query.Query.limit` for
more information on this method.
Args:
count (int): Maximum number of documents to return that match
the query.
Returns:
~.firestore_v1beta1.query.Query: A limited query.
"""
query = query_mod.Query(self)
return query.limit(count)
def offset(self, num_to_skip):
"""Skip to an offset in a query with this collection as parent.
See
:meth:`~.firestore_v1beta1.query.Query.offset` for
more information on this method.
Args:
num_to_skip (int): The number of results to skip at the beginning
of query results. (Must be non-negative.)
Returns:
~.firestore_v1beta1.query.Query: An offset query.
"""
query = query_mod.Query(self)
return query.offset(num_to_skip)
def select(self, field_paths):
"""Create a "select" query with this collection as parent.
See
:meth:`~.firestore_v1beta1.query.Query.select` for
more information on this method.
Args:
field_paths (Iterable[str, ...]): An iterable of field paths
(``.``-delimited list of field names) to use as a projection
of document fields in the query results.
Returns:
~.firestore_v1beta1.query.Query: A "projected" query.
"""
query = query_mod.Query(self)
return query.select(field_paths)
def end_at(self, document_fields):
"""End query at a cursor with this collection as parent.
See
:meth:`~.firestore_v1beta1.query.Query.end_at` for
more information on this method.
Args:
document_fields (Union[~.firestore_v1beta1.\
document.DocumentSnapshot, dict, list, tuple]): a document
snapshot or a dictionary/list/tuple of fields representing a
query results cursor. A cursor is a collection of values that
represent a position in a query result set.
Returns:
~.firestore_v1beta1.query.Query: A query with cursor.
"""
query = query_mod.Query(self)
return query.end_at(document_fields)
def start_after(self, document_fields):
"""Start query after a cursor with this collection as parent.
See
:meth:`~.firestore_v1beta1.query.Query.start_after` for
more information on this method.
Args:
document_fields (Union[~.firestore_v1beta1.\
document.DocumentSnapshot, dict]): Either a document snapshot
or a dictionary of fields representing a query results
cursor. A cursor is a collection of values that represent a
position in a query result set.
Returns:
~.firestore_v1beta1.query.Query: A query with cursor.
"""
query = query_mod.Query(self)
return query.start_after(document_fields)
def order_by(self, field_path, **kwargs):
"""Create an "order by" query with this collection as parent.
See
:meth:`~.firestore_v1beta1.query.Query.order_by` for
more information on this method.
Args:
field_path (str): A field path (``.``-delimited list of
field names) on which to order the query results.
kwargs (Dict[str, Any]): The keyword arguments to pass along
to the query. The only supported keyword is ``direction``,
see :meth:`~.firestore_v1beta1.query.Query.order_by` for
more information.
Returns:
~.firestore_v1beta1.query.Query: An "order by" query.
"""
query = query_mod.Query(self)
return query.order_by(field_path, **kwargs)
def get(self, transaction=None):
"""Read the documents in this collection.
This sends a ``RunQuery`` RPC and then consumes each document
returned in the stream of ``RunQueryResponse`` messages.
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).
Args:
transaction (Optional[~.firestore_v1beta1.transaction.\
Transaction]): An existing transaction that the query will
run in.
Yields:
~.firestore_v1beta1.document.DocumentSnapshot: The next
document that fulfills the query.
"""
query = query_mod.Query(self)
return query.get(transaction=transaction)
def where(self, field_path, op_string, value):
"""Create a "where" query with this collection as parent.
See
:meth:`~.firestore_v1beta1.query.Query.where` for
more information on this method.
Args:
field_path (str): A field path (``.``-delimited list of
field names) for the field to filter on.
op_string (str): A comparison operation in the form of a string.
Acceptable values are ``<``, ``<=``, ``==``, ``>=``
and ``>``.
value (Any): The value to compare the field against in the filter.
If ``value`` is :data:`None` or a NaN, then ``==`` is the only
allowed operation.
Returns:
~.firestore_v1beta1.query.Query: A filtered query.
"""
query = query_mod.Query(self)
return query.where(field_path, op_string, value)