feat(firestore): Added multiple firestore database support

firebase_admin/_utils.py

@@ -93,8 +93,10 @@ def _get_initialized_app(app):
 
 
 
-def get_app_service(app, name, initializer):
+def get_app_service(app, name, initializer, options=None):
     app = _get_initialized_app(app)
+    if options:
+        app.options._options.update(options)
     return app._get_service(name, initializer) # pylint: disable=protected-access
 
 

firebase_admin/firestore.py

@@ -29,16 +29,17 @@
                       'to install the "google-cloud-firestore" module.')
 
 from firebase_admin import _utils
-
+from packaging.version import Version
 
 _FIRESTORE_ATTRIBUTE = '_firestore'
 
 
-def client(app=None):
+def client(app=None, database_id=None):
     """Returns a client that can be used to interact with Google Cloud Firestore.
 
     Args:
       app: An App instance (optional).
+      database_id: The ID of the Google Cloud Firestore database to use. If none provided, default database will be used (optional).
 
     Returns:
       google.cloud.firestore.Firestore: A `Firestore Client`_.
@@ -50,15 +51,27 @@ def client(app=None):
     .. _Firestore Client: https://googlecloudplatform.github.io/google-cloud-python/latest\
           /firestore/client.html
     """
-    fs_client = _utils.get_app_service(app, _FIRESTORE_ATTRIBUTE, _FirestoreClient.from_app)
+
+    options = {"database_id": database_id} if database_id else None
+
+    fs_client = _utils.get_app_service(app, _FIRESTORE_ATTRIBUTE, _FirestoreClient.from_app, options=options)
     return fs_client.get()
 
 
 class _FirestoreClient:
     """Holds a Google Cloud Firestore client instance."""
 
-    def __init__(self, credentials, project):
-        self._client = firestore.Client(credentials=credentials, project=project)
+    def __init__(self, credentials, project, database_id=None):
+        if database_id:
+            if Version(firestore.__version__) < Version("2.12.0"):
+                raise ValueError(
+                    'The database_id parameter is only supported for google-cloud-firestore version '
+                    '2.12.0 and above. Please upgrade your google-cloud-firestore package to use '
+                    'this feature.')
+            self._client = firestore.Client(credentials=credentials, project=project, database=database_id)
+        else:
+            self._client = firestore.Client(credentials=credentials, project=project)
+
 
     def get(self):
         return self._client
@@ -68,9 +81,10 @@ def from_app(cls, app):
         """Creates a new _FirestoreClient for the specified app."""
         credentials = app.credential.get_credential()
         project = app.project_id
+        database_id = app.options.get('database_id')
         if not project:
             raise ValueError(
                 'Project ID is required to access Firestore. Either set the projectId option, '
                 'or use service account credentials. Alternatively, set the GOOGLE_CLOUD_PROJECT '
                 'environment variable.')
-        return _FirestoreClient(credentials, project)
+        return _FirestoreClient(credentials, project, database_id)

tests/test_firestore.py

@@ -65,6 +65,13 @@ def test_service_account(self):
         assert client is not None
         assert client.project == 'mock-project-id'
 
+    def test_service_account_with_explicit_database_id(self):
+        cred = credentials.Certificate(testutils.resource_filename('service_account.json'))
+        firebase_admin.initialize_app(cred)
+        client = firestore.client(database_id='explicit-database-id')
+        assert client is not None
+        assert client._database == 'explicit-database-id'
+
     def test_service_account_with_explicit_app(self):
         cred = credentials.Certificate(testutils.resource_filename('service_account.json'))
         app = firebase_admin.initialize_app(cred)