async_client.py

# Copyright 2020 Google LLC All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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"""Client for interacting with the Google Cloud Firestore API.

This is the base from which all interactions with the API occur.

In the hierarchy of API concepts

* a :class:`~google.cloud.firestore_v1.client.Client` owns a
  :class:`~google.cloud.firestore_v1.async_collection.AsyncCollectionReference`
* a :class:`~google.cloud.firestore_v1.client.Client` owns a
  :class:`~google.cloud.firestore_v1.async_document.AsyncDocumentReference`
"""

from google.cloud.firestore_v1.base_client import (
    BaseClient,
    DEFAULT_DATABASE,
    _CLIENT_INFO,
    _reference_info,  # type: ignore
    _parse_batch_get,  # type: ignore
    _get_doc_mask,
    _path_helper,
)

from google.cloud.firestore_v1 import _helpers
from google.cloud.firestore_v1.async_query import AsyncCollectionGroup
from google.cloud.firestore_v1.async_batch import AsyncWriteBatch
from google.cloud.firestore_v1.async_collection import AsyncCollectionReference
from google.cloud.firestore_v1.async_document import (
    AsyncDocumentReference,
    DocumentSnapshot,
)
from google.cloud.firestore_v1.async_transaction import AsyncTransaction
from google.cloud.firestore_v1.services.firestore import (
    async_client as firestore_client,
)
from google.cloud.firestore_v1.services.firestore.transports import (
    grpc_asyncio as firestore_grpc_transport,
)
from typing import Any, AsyncGenerator, Iterable, Tuple


class AsyncClient(BaseClient):
    """Client for interacting with Google Cloud Firestore API.

    .. note::

        Since the Cloud Firestore API requires the gRPC transport, no
        ``_http`` argument is accepted by this class.

    Args:
        project (Optional[str]): The project which the client acts on behalf
            of. If not passed, falls back to the default inferred
            from the environment.
        credentials (Optional[~google.auth.credentials.Credentials]): The
            OAuth2 Credentials to use for this client. If not passed, falls
            back to the default inferred from the environment.
        database (Optional[str]): The database name that the client targets.
            For now, :attr:`DEFAULT_DATABASE` (the default value) is the
            only valid database.
        client_info (Optional[google.api_core.gapic_v1.client_info.ClientInfo]):
            The client info used to send a user-agent string along with API
            requests. If ``None``, then default info will be used. Generally,
            you only need to set this if you're developing your own library
            or partner tool.
        client_options (Union[dict, google.api_core.client_options.ClientOptions]):
            Client options used to set user options on the client. API Endpoint
            should be set through client_options.
    """

    def __init__(
        self,
        project=None,
        credentials=None,
        database=DEFAULT_DATABASE,
        client_info=_CLIENT_INFO,
        client_options=None,
    ) -> None:
        super(AsyncClient, self).__init__(
            project=project,
            credentials=credentials,
            database=database,
            client_info=client_info,
            client_options=client_options,
        )

    @property
    def _firestore_api(self):
        """Lazy-loading getter GAPIC Firestore API.
        Returns:
            :class:`~google.cloud.gapic.firestore.v1`.async_firestore_client.FirestoreAsyncClient:
            The GAPIC client with the credentials of the current client.
        """
        return self._firestore_api_helper(
            firestore_grpc_transport.FirestoreGrpcAsyncIOTransport,
            firestore_client.FirestoreAsyncClient,
            firestore_client,
        )

    @property
    def _target(self):
        """Return the target (where the API is).
        Eg. "firestore.googleapis.com"

        Returns:
            str: The location of the API.
        """
        return self._target_helper(firestore_client.FirestoreAsyncClient)

    def collection(self, *collection_path: Tuple[str]) -> AsyncCollectionReference:
        """Get a reference to a collection.

        For a top-level collection:

        .. code-block:: python

            >>> client.collection('top')

        For a sub-collection:

        .. code-block:: python

            >>> client.collection('mydocs/doc/subcol')
            >>> # is the same as
            >>> client.collection('mydocs', 'doc', 'subcol')

        Sub-collections can be nested deeper in a similar fashion.

        Args:
            collection_path (Tuple[str, ...]): Can either be

                * A single ``/``-delimited path to a collection
                * A tuple of collection path segments

        Returns:
            :class:`~google.cloud.firestore_v1.async_collection.AsyncCollectionReference`:
            A reference to a collection in the Firestore database.
        """
        return AsyncCollectionReference(*_path_helper(collection_path), client=self)

    def collection_group(self, collection_id: str) -> AsyncCollectionGroup:
        """
        Creates and returns a new AsyncQuery that includes all documents in the
        database that are contained in a collection or subcollection with the
        given collection_id.

        .. code-block:: python

            >>> query = client.collection_group('mygroup')

        Args:
            collection_id (str) Identifies the collections to query over.

                Every collection or subcollection with this ID as the last segment of its
                path will be included. Cannot contain a slash.

        Returns:
            :class:`~google.cloud.firestore_v1.async_query.AsyncCollectionGroup`:
            The created AsyncQuery.
        """
        return AsyncCollectionGroup(self._get_collection_reference(collection_id))

    def document(self, *document_path: Tuple[str]) -> AsyncDocumentReference:
        """Get a reference to a document in a collection.

        For a top-level document:

        .. code-block:: python

            >>> client.document('collek/shun')
            >>> # is the same as
            >>> client.document('collek', 'shun')

        For a document in a sub-collection:

        .. code-block:: python

            >>> client.document('mydocs/doc/subcol/child')
            >>> # is the same as
            >>> client.document('mydocs', 'doc', 'subcol', 'child')

        Documents in sub-collections can be nested deeper in a similar fashion.

        Args:
            document_path (Tuple[str, ...]): Can either be

                * A single ``/``-delimited path to a document
                * A tuple of document path segments

        Returns:
            :class:`~google.cloud.firestore_v1.document.AsyncDocumentReference`:
            A reference to a document in a collection.
        """
        return AsyncDocumentReference(
            *self._document_path_helper(*document_path), client=self
        )

    async def get_all(
        self, references: list, field_paths: Iterable[str] = None, transaction=None,
    ) -> AsyncGenerator[DocumentSnapshot, Any]:
        """Retrieve a batch of documents.

        .. note::

           Documents returned by this method are not guaranteed to be
           returned in the same order that they are given in ``references``.

        .. note::

           If multiple ``references`` refer to the same document, the server
           will only return one result.

        See :meth:`~google.cloud.firestore_v1.client.Client.field_path` for
        more information on **field paths**.

        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:
            references (List[.AsyncDocumentReference, ...]): Iterable of document
                references to be retrieved.
            field_paths (Optional[Iterable[str, ...]]): An iterable of field
                paths (``.``-delimited list of field names) to use as a
                projection of document fields in the returned results. If
                no value is provided, all fields will be returned.
            transaction (Optional[:class:`~google.cloud.firestore_v1.async_transaction.AsyncTransaction`]):
                An existing transaction that these ``references`` will be
                retrieved in.

        Yields:
            .DocumentSnapshot: The next document snapshot that fulfills the
            query, or :data:`None` if the document does not exist.
        """
        document_paths, reference_map = _reference_info(references)
        mask = _get_doc_mask(field_paths)
        response_iterator = await self._firestore_api.batch_get_documents(
            request={
                "database": self._database_string,
                "documents": document_paths,
                "mask": mask,
                "transaction": _helpers.get_transaction_id(transaction),
            },
            metadata=self._rpc_metadata,
        )

        async for get_doc_response in response_iterator:
            yield _parse_batch_get(get_doc_response, reference_map, self)

    async def collections(self) -> AsyncGenerator[AsyncCollectionReference, Any]:
        """List top-level collections of the client's database.

        Returns:
            Sequence[:class:`~google.cloud.firestore_v1.async_collection.AsyncCollectionReference`]:
                iterator of subcollections of the current document.
        """
        iterator = await self._firestore_api.list_collection_ids(
            request={"parent": "{}/documents".format(self._database_string)},
            metadata=self._rpc_metadata,
        )

        while True:
            for i in iterator.collection_ids:
                yield self.collection(i)
            if iterator.next_page_token:
                iterator = await self._firestore_api.list_collection_ids(
                    request={
                        "parent": "{}/documents".format(self._database_string),
                        "page_token": iterator.next_page_token,
                    },
                    metadata=self._rpc_metadata,
                )
            else:
                return

        # TODO(microgen): currently this method is rewritten to iterate/page itself.
        # https://github.com/googleapis/gapic-generator-python/issues/516
        # it seems the generator ought to be able to do this itself.
        # iterator.client = self
        # iterator.item_to_value = _item_to_collection_ref
        # return iterator

    def batch(self) -> AsyncWriteBatch:
        """Get a batch instance from this client.

        Returns:
            :class:`~google.cloud.firestore_v1.async_batch.AsyncWriteBatch`:
            A "write" batch to be used for accumulating document changes and
            sending the changes all at once.
        """
        return AsyncWriteBatch(self)

    def transaction(self, **kwargs) -> AsyncTransaction:
        """Get a transaction that uses this client.

        See :class:`~google.cloud.firestore_v1.async_transaction.AsyncTransaction` for
        more information on transactions and the constructor arguments.

        Args:
            kwargs (Dict[str, Any]): The keyword arguments (other than
                ``client``) to pass along to the
                :class:`~google.cloud.firestore_v1.async_transaction.AsyncTransaction`
                constructor.

        Returns:
            :class:`~google.cloud.firestore_v1.async_transaction.AsyncTransaction`:
            A transaction attached to this client.
        """
        return AsyncTransaction(self, **kwargs)