Added lazy initialization to table object

Author: gkevinzheng

google/cloud/bigtable/table.py

@@ -132,17 +132,9 @@ def __init__(self, table_id, instance, mutation_timeout=None, app_profile_id=Non
         self._app_profile_id = app_profile_id
         self.mutation_timeout = mutation_timeout
 
-        # TODO: Figure out which value to use for mutation_timeout after looking at how
-        # mutation_timeout is used in this class.
-        self._table_impl = (
-            self._instance._client._veneer_data_client.get_table(
-                self._instance.instance_id,
-                self.table_id,
-                app_profile_id=app_profile_id,
-            )
-            if self._instance
-            else None
-        )
+        # Lazily initialize the table shim to avoid causing constructor errors for instance=None
+        # that don't exist in the original implementation.
+        self._table_impl = None
 
     @property
     def name(self):
@@ -174,6 +166,18 @@ def name(self):
             project=project, instance=instance_id, table=self.table_id
         )
 
+    @property
+    def _veneer_data_table(self):
+        """Getter for the data client table representation of this object."""
+        if self._table_impl is None:
+            self._table_impl = self._instance._client._veneer_data_client.get_table(
+                self._instance.instance_id,
+                self.table_id,
+                app_profile_id=self._app_profile_id,
+            )
+
+        return self._table_impl
+
     def get_iam_policy(self):
         """Gets the IAM access control policy for this table.
 

tests/unit/v2_client/test_table.py

@@ -162,6 +162,35 @@ def _make_table(*args, **kwargs):
 
 
 def test_table_constructor_defaults():
+    instance = mock.Mock(spec=[])
+
+    table = _make_table(TABLE_ID, instance)
+
+    assert table.table_id == TABLE_ID
+    assert table._instance is instance
+    assert table.mutation_timeout is None
+    assert table._app_profile_id is None
+
+
+def test_table_constructor_explicit():
+    instance = mock.Mock(spec=[])
+    mutation_timeout = 123
+    app_profile_id = "profile-123"
+
+    table = _make_table(
+        TABLE_ID,
+        instance,
+        mutation_timeout=mutation_timeout,
+        app_profile_id=app_profile_id,
+    )
+
+    assert table.table_id == TABLE_ID
+    assert table._instance is instance
+    assert table.mutation_timeout == mutation_timeout
+    assert table._app_profile_id == app_profile_id
+
+
+def test_table_name():
     table_data_client = mock.Mock(spec=["table_path"])
     _veneer_data_client = mock.Mock()
     client = mock.Mock(
@@ -178,17 +207,35 @@ def test_table_constructor_defaults():
 
     table = _make_table(TABLE_ID, instance)
 
-    assert table.table_id == TABLE_ID
-    assert table._instance is instance
-    assert table.mutation_timeout is None
-    assert table._app_profile_id is None
-    assert table._table_impl == _veneer_data_client.get_table.return_value
+    assert table.name == table_data_client.table_path.return_value
+
+
+def test_table_veneer_data_table_not_initialized_defaults():
+    table_data_client = mock.Mock(spec=["table_path"])
+    _veneer_data_client = mock.Mock()
+    client = mock.Mock(
+        project=PROJECT_ID,
+        table_data_client=table_data_client,
+        _veneer_data_client=_veneer_data_client,
+        spec=["project", "table_data_client", "_veneer_data_client"],
+    )
+    instance = mock.Mock(
+        _client=client,
+        instance_id=INSTANCE_ID,
+        spec=["_client", "instance_id"],
+    )
+
+    table = _make_table(TABLE_ID, instance)
+    table._veneer_data_table
+
     _veneer_data_client.get_table.assert_called_once_with(
-        INSTANCE_ID, TABLE_ID, app_profile_id=None
+        INSTANCE_ID,
+        TABLE_ID,
+        app_profile_id=None,
     )
 
 
-def test_table_constructor_explicit():
+def test_table_veneer_data_table_not_initialized_explicit():
     table_data_client = mock.Mock(spec=["table_path"])
     _veneer_data_client = mock.Mock()
     client = mock.Mock(
@@ -202,29 +249,23 @@ def test_table_constructor_explicit():
         instance_id=INSTANCE_ID,
         spec=["_client", "instance_id"],
     )
-    mutation_timeout = 123
-    app_profile_id = "profile-123"
 
+    app_profile_id = "profile-123"
     table = _make_table(
         TABLE_ID,
         instance,
-        mutation_timeout=mutation_timeout,
         app_profile_id=app_profile_id,
     )
+    table._veneer_data_table
 
-    assert table.table_id == TABLE_ID
-    assert table._instance is instance
-    assert table.mutation_timeout == mutation_timeout
-    assert table._app_profile_id == app_profile_id
-    assert table._table_impl == _veneer_data_client.get_table.return_value
     _veneer_data_client.get_table.assert_called_once_with(
         INSTANCE_ID,
         TABLE_ID,
         app_profile_id=app_profile_id,
     )
 
 
-def test_table_name():
+def test_table_veneer_data_table_initialized():
     table_data_client = mock.Mock(spec=["table_path"])
     _veneer_data_client = mock.Mock()
     client = mock.Mock(
@@ -240,8 +281,9 @@ def test_table_name():
     )
 
     table = _make_table(TABLE_ID, instance)
-
-    assert table.name == table_data_client.table_path.return_value
+    already = table._table_impl = object()
+    assert table._veneer_data_table is already
+    _veneer_data_client.get_table.assert_not_called()
 
 
 def _table_row_methods_helper():