Adding HTTP support to core Operation class.

Will likely need updates to Speech operation class.

core/google/cloud/operation.py

@@ -15,6 +15,7 @@
 """Wrap long-running operations returned from Google Cloud APIs."""
 
 from google.longrunning import operations_pb2
+from google.protobuf import json_format
 
 
 _GOOGLE_APIS_PREFIX = 'type.googleapis.com'
@@ -97,8 +98,13 @@ class Operation(object):
     :type name: str
     :param name: The fully-qualified path naming the operation.
 
-    :type client: object: must provide ``_operations_stub`` accessor.
+    :type client: :class:`~google.cloud.client.Client`
     :param client: The client used to poll for the status of the operation.
+                   If the operation was created via JSON/HTTP, the client
+                   must own a :class:`~google.cloud.connection.Connection`
+                   to send polling requests. If created via protobuf, the
+                   client must have a gRPC stub in the ``_operations_stub``
+                   attribute.
 
     :type caller_metadata: dict
     :param caller_metadata: caller-assigned metadata about the operation
@@ -127,6 +133,8 @@ class Operation(object):
     converted into the correct types.
     """
 
+    _use_grpc = True
+
     def __init__(self, name, client, **caller_metadata):
         self.name = name
         self.client = client
@@ -152,6 +160,30 @@ def from_pb(cls, operation_pb, client, **caller_metadata):
         """
         result = cls(operation_pb.name, client, **caller_metadata)
         result._update_state(operation_pb)
+        result._use_grpc = True
+        return result
+
+    @classmethod
+    def from_dict(cls, operation, client, **caller_metadata):
+        """Factory: construct an instance from a dictionary.
+
+        :type operation: dict
+        :param operation: Operation as a JSON object.
+
+        :type client: :class:`~google.cloud.client.Client`
+        :param client: The client used to poll for the status of the operation.
+
+        :type caller_metadata: dict
+        :param caller_metadata: caller-assigned metadata about the operation
+
+        :rtype: :class:`Operation`
+        :returns: new instance, with attributes based on the protobuf.
+        """
+        operation_pb = json_format.ParseDict(
+            operation, operations_pb2.Operation())
+        result = cls(operation_pb.name, client, **caller_metadata)
+        result._update_state(operation_pb)
+        result._use_grpc = False
         return result
 
     @property
@@ -166,12 +198,39 @@ def complete(self):
     def _get_operation_rpc(self):
         """Checks the status of the current operation.
 
+        Uses gRPC request to check.
+
         :rtype: :class:`~google.longrunning.operations_pb2.Operation`
         :returns: The latest status of the current operation.
         """
         request_pb = operations_pb2.GetOperationRequest(name=self.name)
         return self.client._operations_stub.GetOperation(request_pb)
 
+    def _get_operation_http(self):
+        """Checks the status of the current operation.
+
+        Uses HTTP request to check.
+
+        :rtype: :class:`~google.longrunning.operations_pb2.Operation`
+        :returns: The latest status of the current operation.
+        """
+        path = 'operations/%s' % (self.name,)
+        api_response = self.client.connection.api_request(
+            method='GET', path=path)
+        return json_format.ParseDict(
+            api_response, operations_pb2.Operation())
+
+    def _get_operation(self):
+        """Checks the status of the current operation.
+
+        :rtype: :class:`~google.longrunning.operations_pb2.Operation`
+        :returns: The latest status of the current operation.
+        """
+        if self._use_grpc:
+            return self._get_operation_rpc()
+        else:
+            return self._get_operation_http()
+
     def _update_state(self, operation_pb):
         """Update the state of the current object based on operation.
 
@@ -202,7 +261,7 @@ def poll(self):
         if self.complete:
             raise ValueError('The operation has completed.')
 
-        operation_pb = self._get_operation_rpc()
+        operation_pb = self._get_operation()
         self._update_state(operation_pb)
 
         return self.complete

core/unit_tests/test_operation.py

@@ -88,7 +88,7 @@ def test_w_conflict(self):
         self.assertEqual(type_url_map, {TYPE_URI: other})
 
 
-class OperationTests(unittest.TestCase):
+class TestOperation(unittest.TestCase):
 
     OPERATION_NAME = 'operations/projects/foo/instances/bar/operations/123'
 
@@ -110,6 +110,7 @@ def test_ctor_defaults(self):
         self.assertIsNone(operation.error)
         self.assertIsNone(operation.metadata)
         self.assertEqual(operation.caller_metadata, {})
+        self.assertTrue(operation._use_grpc)
 
     def test_ctor_explicit(self):
         client = _Client()
@@ -123,6 +124,7 @@ def test_ctor_explicit(self):
         self.assertIsNone(operation.error)
         self.assertIsNone(operation.metadata)
         self.assertEqual(operation.caller_metadata, {'foo': 'bar'})
+        self.assertTrue(operation._use_grpc)
 
     def test_from_pb_wo_metadata_or_kw(self):
         from google.longrunning import operations_pb2
@@ -187,6 +189,38 @@ def test_from_pb_w_metadata_and_kwargs(self):
         self.assertEqual(operation.metadata, meta)
         self.assertEqual(operation.caller_metadata, {'baz': 'qux'})
 
+    def test_from_dict(self):
+        from google.protobuf.struct_pb2 import Struct
+        from google.cloud._testing import _Monkey
+        from google.cloud import operation as MUT
+
+        type_url = 'type.googleapis.com/%s' % (Struct.DESCRIPTOR.full_name,)
+        api_response = {
+            'name': self.OPERATION_NAME,
+            'metadata': {
+                '@type': type_url,
+                'value': {'foo': 'Bar'},
+            },
+        }
+
+        client = _Client()
+        klass = self._getTargetClass()
+
+        with _Monkey(MUT, _TYPE_URL_MAP={type_url: Struct}):
+            operation = klass.from_dict(api_response, client)
+
+        self.assertEqual(operation.name, self.OPERATION_NAME)
+        self.assertIs(operation.client, client)
+        self.assertIsNone(operation.target)
+        self.assertIsNone(operation.response)
+        self.assertIsNone(operation.error)
+        self.assertIsInstance(operation.metadata, Struct)
+        self.assertEqual(len(operation.metadata.fields), 1)
+        self.assertEqual(
+            operation.metadata.fields['foo'].string_value, 'Bar')
+        self.assertEqual(operation.caller_metadata, {})
+        self.assertFalse(operation._use_grpc)
+
     def test_complete_property(self):
         client = _Client()
         operation = self._makeOne(self.OPERATION_NAME, client)
@@ -234,6 +268,35 @@ def test_poll_true(self):
         self.assertIsInstance(request_pb, operations_pb2.GetOperationRequest)
         self.assertEqual(request_pb.name, self.OPERATION_NAME)
 
+    def test_poll_http(self):
+        from google.protobuf.struct_pb2 import Struct
+        from google.cloud._testing import _Monkey
+        from google.cloud import operation as MUT
+
+        type_url = 'type.googleapis.com/%s' % (Struct.DESCRIPTOR.full_name,)
+        name = '2302903294023'
+        api_response = {
+            'name': name,
+            'done': True,
+            'metadata': {
+                '@type': type_url,
+                'value': {'foo': 'Bar'},
+            },
+        }
+        connection = _Connection(api_response)
+        client = _Client(connection)
+        operation = self._makeOne(name, client)
+        operation._use_grpc = False
+
+        with _Monkey(MUT, _TYPE_URL_MAP={type_url: Struct}):
+            self.assertTrue(operation.poll())
+
+        expected_path = 'operations/%s' % (name,)
+        self.assertEqual(connection._requested, [{
+            'method': 'GET',
+            'path': expected_path,
+        }])
+
     def test__update_state_done(self):
         from google.longrunning import operations_pb2
 
@@ -324,7 +387,20 @@ def GetOperation(self, request_pb):
         return self._get_operation_response
 
 
+class _Connection(object):
+
+    def __init__(self, *responses):
+        self._responses = responses
+        self._requested = []
+
+    def api_request(self, **kw):
+        self._requested.append(kw)
+        response, self._responses = self._responses[0], self._responses[1:]
+        return response
+
+
 class _Client(object):
 
-    def __init__(self):
+    def __init__(self, connection=None):
         self._operations_stub = _OperationsStub()
+        self.connection = connection