BigQuery: Adds client.get_dataset() and removes dataset.reload() (#3973)

* BigQuery: Adds client.get_dataset() and removes dataset.reload()

* BigQuery: changes dataset.name to dataset.dataset_id in test

* fixes client.get_dataset() docstring and removes unnecessary test variable

bigquery/google/cloud/bigquery/client.py

@@ -166,6 +166,20 @@ def dataset(self, dataset_name, project=None):
 
         return DatasetReference(project, dataset_name)
 
+    def get_dataset(self, dataset_ref):
+        """Fetch the dataset referenced by ``dataset_ref``
+
+        :type dataset_ref:
+            :class:`google.cloud.bigquery.dataset.DatasetReference`
+        :param dataset_ref: the dataset to use.
+
+        :rtype: :class:`google.cloud.bigquery.dataset.Dataset`
+        :returns: a ``Dataset`` instance
+        """
+        api_response = self._connection.api_request(
+            method='GET', path=dataset_ref.path)
+        return Dataset.from_api_repr(api_response, self)
+
     def _get_query_results(self, job_id, project=None, timeout_ms=None):
         """Get the query results object for a query job.
 

bigquery/google/cloud/bigquery/dataset.py

@@ -127,6 +127,15 @@ def dataset_id(self):
         """
         return self._dataset_id
 
+    @property
+    def path(self):
+        """URL path for the dataset's APIs.
+
+        :rtype: str
+        :returns: the path based on project and dataset name.
+        """
+        return '/projects/%s/datasets/%s' % (self.project_id, self.dataset_id)
+
     def table(self, table_id):
         """Constructs a TableReference.
 
@@ -505,23 +514,6 @@ def exists(self, client=None):
         else:
             return True
 
-    def reload(self, client=None):
-        """API call:  refresh dataset properties via a GET request.
-
-        See
-        https://cloud.google.com/bigquery/docs/reference/rest/v2/datasets/get
-
-        :type client: :class:`~google.cloud.bigquery.client.Client` or
-                      ``NoneType``
-        :param client: the client to use.  If not passed, falls back to the
-                       ``client`` stored on the current dataset.
-        """
-        client = self._require_client(client)
-
-        api_response = client._connection.api_request(
-            method='GET', path=self.path)
-        self._set_properties(api_response)
-
     def patch(self, client=None, **kw):
         """API call:  update individual dataset properties via a PATCH request.
 

bigquery/tests/system.py

@@ -121,19 +121,20 @@ def test_create_dataset(self):
         self.assertTrue(dataset.exists())
         self.assertEqual(dataset.dataset_id, DATASET_ID)
 
-    def test_reload_dataset(self):
-        DATASET_ID = _make_dataset_id('reload_dataset')
-        dataset = Dataset(DATASET_ID, Config.CLIENT)
+    def test_get_dataset(self):
+        DATASET_ID = _make_dataset_id('get_dataset')
+        client = Config.CLIENT
+        dataset = Dataset(DATASET_ID, client)
         dataset.friendly_name = 'Friendly'
         dataset.description = 'Description'
-
         retry_403(dataset.create)()
         self.to_delete.append(dataset)
+        dataset_ref = client.dataset(DATASET_ID)
+
+        got = client.get_dataset(dataset_ref)
 
-        other = Dataset(DATASET_ID, Config.CLIENT)
-        other.reload()
-        self.assertEqual(other.friendly_name, 'Friendly')
-        self.assertEqual(other.description, 'Description')
+        self.assertEqual(got.friendly_name, 'Friendly')
+        self.assertEqual(got.description, 'Description')
 
     def test_patch_dataset(self):
         dataset = Dataset(_make_dataset_id('patch_dataset'), Config.CLIENT)

bigquery/tests/unit/test_client.py

@@ -272,6 +272,31 @@ def test_dataset_with_default_project(self):
         self.assertEqual(dataset.dataset_id, DATASET)
         self.assertEqual(dataset.project_id, PROJECT)
 
+    def test_get_dataset(self):
+        project = 'PROJECT'
+        dataset_id = 'dataset_id'
+        path = 'projects/%s/datasets/%s' % (project, dataset_id)
+        creds = _make_credentials()
+        http = object()
+        client = self._make_one(project=project, credentials=creds, _http=http)
+        resource = {
+            'id': '%s:%s' % (project, dataset_id),
+            'datasetReference': {
+                'projectId': project,
+                'datasetId': dataset_id,
+            },
+        }
+        conn = client._connection = _Connection(resource)
+        dataset_ref = client.dataset(dataset_id)
+
+        dataset = client.get_dataset(dataset_ref)
+
+        self.assertEqual(len(conn._requested), 1)
+        req = conn._requested[0]
+        self.assertEqual(req['method'], 'GET')
+        self.assertEqual(req['path'], '/%s' % path)
+        self.assertEqual(dataset.dataset_id, dataset_id)
+
     def test_job_from_resource_unknown_type(self):
         PROJECT = 'PROJECT'
         creds = _make_credentials()

bigquery/tests/unit/test_dataset.py

@@ -520,39 +520,6 @@ def test_exists_hit_w_alternate_client(self):
         self.assertEqual(req['path'], '/%s' % PATH)
         self.assertEqual(req['query_params'], {'fields': 'id'})
 
-    def test_reload_w_bound_client(self):
-        PATH = 'projects/%s/datasets/%s' % (self.PROJECT, self.DS_ID)
-        RESOURCE = self._makeResource()
-        conn = _Connection(RESOURCE)
-        client = _Client(project=self.PROJECT, connection=conn)
-        dataset = self._make_one(self.DS_ID, client=client)
-
-        dataset.reload()
-
-        self.assertEqual(len(conn._requested), 1)
-        req = conn._requested[0]
-        self.assertEqual(req['method'], 'GET')
-        self.assertEqual(req['path'], '/%s' % PATH)
-        self._verify_resource_properties(dataset, RESOURCE)
-
-    def test_reload_w_alternate_client(self):
-        PATH = 'projects/%s/datasets/%s' % (self.PROJECT, self.DS_ID)
-        RESOURCE = self._makeResource()
-        conn1 = _Connection()
-        CLIENT1 = _Client(project=self.PROJECT, connection=conn1)
-        conn2 = _Connection(RESOURCE)
-        CLIENT2 = _Client(project=self.PROJECT, connection=conn2)
-        dataset = self._make_one(self.DS_ID, client=CLIENT1)
-
-        dataset.reload(client=CLIENT2)
-
-        self.assertEqual(len(conn1._requested), 0)
-        self.assertEqual(len(conn2._requested), 1)
-        req = conn2._requested[0]
-        self.assertEqual(req['method'], 'GET')
-        self.assertEqual(req['path'], '/%s' % PATH)
-        self._verify_resource_properties(dataset, RESOURCE)
-
     def test_patch_w_invalid_expiration(self):
         RESOURCE = self._makeResource()
         conn = _Connection(RESOURCE)