feat: wire database parameter through parse_url and dialect

Extract `database` from URL query params in parse_url() and pass it
through create_connect_args() to create_datastore_client(), enabling
users to target non-default Datastore databases via the connection
URI (e.g. `datastore://project/?database=my-db`).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: splasky

sqlalchemy_datastore/base.py

@@ -83,6 +83,7 @@ def __init__(
         self.location = location
         self.identifier_preparer = self.preparer(self)
         self.dataset_id = None
+        self.database_id = None
         self.list_tables_page_size = list_tables_page_size
         self._client = None
 
@@ -124,6 +125,7 @@ def create_connect_args(self, url):
             provided_job_config,
             list_tables_page_size,
             user_supplied_client,
+            database_id,
         ) = parse_url(url)
 
         self.arraysize = arraysize or self.arraysize
@@ -133,6 +135,7 @@ def create_connect_args(self, url):
         self.credentials_path = credentials_path
         self.credentials_base64 = credentials_base64 or self.credentials_base64
         self.dataset_id = dataset_id
+        self.database_id = database_id
         self.billing_project_id = self.billing_project_id or self.project_id
 
         if user_supplied_client:
@@ -143,7 +146,7 @@ def create_connect_args(self, url):
                 credentials_info=self.credentials_info,
                 credentials_base64=self.credentials_base64,
                 project_id=self.billing_project_id,
-                database=None,
+                database=self.database_id,
             )
             self.project_id = self.project_id if self.project_id else client.project
             self.billing_project_id = (

sqlalchemy_datastore/parse_url.py

@@ -72,6 +72,11 @@ def parse_url(url):  # noqa: C901
     credentials_base64 = None
     list_tables_page_size = None
     user_supplied_client = False
+    database = None
+
+    # database
+    if "database" in query:
+        database = query.pop("database")
 
     # location
     if "location" in query:
@@ -122,6 +127,7 @@ def parse_url(url):  # noqa: C901
                 QueryJobConfig(),
                 list_tables_page_size,
                 user_supplied_client,
+                database,
             )
         else:
             return (
@@ -134,6 +140,7 @@ def parse_url(url):  # noqa: C901
                 None,
                 list_tables_page_size,
                 user_supplied_client,
+                database,
             )
 
     job_config = QueryJobConfig()
@@ -284,4 +291,5 @@ def parse_url(url):  # noqa: C901
         job_config,
         list_tables_page_size,
         user_supplied_client,
+        database,
     )

tests/test_unit_base.py

@@ -17,9 +17,12 @@
 # IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 """Unit tests for base.py CloudDatastoreDialect (no emulator required)."""
-from unittest.mock import MagicMock
+from unittest.mock import MagicMock, patch
+
+from sqlalchemy.engine.url import make_url
 
 from sqlalchemy_datastore import CloudDatastoreDialect, datastore_dbapi
+from sqlalchemy_datastore.parse_url import parse_url
 
 # ---------------------------------------------------------------------------
 # Dialect metadata
@@ -224,3 +227,78 @@ def test_get_table_names_empty():
 
     result = d.get_table_names(None)
     assert result == []
+
+
+# ---------------------------------------------------------------------------
+# parse_url – database parameter
+# ---------------------------------------------------------------------------
+
+def test_parse_url_extracts_database():
+    url = make_url("datastore://my-project/?database=my-db")
+    result = parse_url(url)
+    assert len(result) == 10
+    assert result[9] == "my-db"
+
+
+def test_parse_url_no_database():
+    url = make_url("datastore://my-project/")
+    result = parse_url(url)
+    assert len(result) == 10
+    assert result[9] is None
+
+
+def test_parse_url_database_with_location():
+    url = make_url("datastore://my-project/?database=my-db&location=us-east1")
+    result = parse_url(url)
+    assert result[9] == "my-db"
+    assert result[1] == "us-east1"
+
+
+# ---------------------------------------------------------------------------
+# create_connect_args – database parameter
+# ---------------------------------------------------------------------------
+
+def test_create_connect_args_passes_database():
+    d = CloudDatastoreDialect()
+    url = make_url("datastore://my-project/?database=my-db")
+
+    with patch(
+        "sqlalchemy_datastore.base.create_datastore_client"
+    ) as mock_create:
+        mock_client = MagicMock()
+        mock_client.project = "my-project"
+        mock_create.return_value = (mock_client, MagicMock())
+
+        d.create_connect_args(url)
+
+        mock_create.assert_called_once_with(
+            credentials_path=None,
+            credentials_info=None,
+            credentials_base64=None,
+            project_id="my-project",
+            database="my-db",
+        )
+        assert d.database_id == "my-db"
+
+
+def test_create_connect_args_no_database():
+    d = CloudDatastoreDialect()
+    url = make_url("datastore://my-project/")
+
+    with patch(
+        "sqlalchemy_datastore.base.create_datastore_client"
+    ) as mock_create:
+        mock_client = MagicMock()
+        mock_client.project = "my-project"
+        mock_create.return_value = (mock_client, MagicMock())
+
+        d.create_connect_args(url)
+
+        mock_create.assert_called_once_with(
+            credentials_path=None,
+            credentials_info=None,
+            credentials_base64=None,
+            project_id="my-project",
+            database=None,
+        )
+        assert d.database_id is None