feat: add rest transport generation for clients with optional flag

gapic/ads-templates/%namespace/%name/%version/__init__.py.j2

@@ -20,6 +20,7 @@ _lazy_type_to_package_map = {
     '{{ enum.name }}': '{{ enum.ident.package|join('.') }}.types.{{enum.ident.module }}',
 {%- endfor %}
 
+    {# TODO(yon-mg): add rest transport service once I know what this is #}
     # Client classes and transports  
 {%- for service in api.services.values() %}
     '{{ service.client_name }}': '{{ service.meta.address.package|join('.') }}.services.{{ service.meta.address.module }}',

gapic/ads-templates/%namespace/%name/__init__.py.j2

@@ -20,6 +20,7 @@ _lazy_type_to_package_map = {
     '{{ enum.name }}': '{{ enum.ident.package|join('.') }}.types.{{enum.ident.module }}',
 {%- endfor %}
 
+    {# TODO(yon-mg): add rest transport service once I know what this is #}
     # Client classes and transports  
 {%- for service in api.services.values() %}
     '{{ service.client_name }}': '{{ service.meta.address.package|join('.') }}.services.{{ service.meta.address.module }}',

gapic/generator/generator.py

@@ -272,8 +272,11 @@ def _render_template(
         if "%service" in template_name:
             for service in api_schema.services.values():
                 if (
-                        skip_subpackages
-                        and service.meta.address.subpackage != api_schema.subpackage_view
+                        (skip_subpackages
+                        and service.meta.address.subpackage != api_schema.subpackage_view)
+                        or
+                        ('transport' in template_name
+                        and not self._is_desired_transport(template_name, opts))
                 ):
                     continue
 
@@ -293,6 +296,11 @@ def _render_template(
             template_name, api_schema=api_schema, opts=opts))
         return answer
 
+    def _is_desired_transport(self, template_name: str, opts: Options) -> bool:
+        """Returns true if template name contains a desired transport"""
+        desired_transports = ['__init__', 'base'] + opts.transport
+        return any(transport in template_name for transport in desired_transports)
+
     def _get_file(
         self,
         template_name: str,

gapic/schema/wrappers.py

@@ -719,6 +719,8 @@ def _client_output(self, enable_asyncio: bool):
         # Return the usual output.
         return self.output
 
+    # TODO(yon-mg): remove or rewrite: don't think it performs as intended
+    #               e.g. doesn't work with basic case of gRPC transcoding
     @property
     def field_headers(self) -> Sequence[str]:
         """Return the field headers defined for this method."""
@@ -737,6 +739,35 @@ def field_headers(self) -> Sequence[str]:
 
         return next((tuple(pattern.findall(verb)) for verb in potential_verbs if verb), ())
 
+    @property
+    def http_opt(self) -> Optional[Dict[str, str]]:
+        """Return the http option for this method.
+
+        e.g. {'verb': 'post'
+              'url': '/some/path'
+              'body': '*'}
+
+        """
+        http: List[Tuple[descriptor_pb2.FieldDescriptorProto, str]]
+        http = self.options.Extensions[annotations_pb2.http].ListFields()
+
+        if len(http) < 1:
+            return None
+
+        http_method = http[0]
+        answer: Dict[str, str] = {
+            'verb': http_method[0].name,
+            'url': http_method[1],
+        }
+        if len(http) > 1:
+            body_spec = http[1]
+            answer[body_spec[0].name] = body_spec[1]
+
+        # TODO(yon-mg): handle nested fields & fields past body i.e. 'additional bindings'
+        # TODO(yon-mg): enums for http verbs?
+        return answer
+
+    # TODO(yon-mg): refactor as there may be more than one method signature
     @utils.cached_property
     def flattened_fields(self) -> Mapping[str, Field]:
         """Return the signature defined for this method."""
@@ -786,6 +817,7 @@ def grpc_stub_type(self) -> str:
             server='stream' if self.server_streaming else 'unary',
         )
 
+    # TODO(yon-mg): figure out why idempotent is reliant on http annotation
     @utils.cached_property
     def idempotent(self) -> bool:
         """Return True if we know this method is idempotent, False otherwise.
@@ -980,6 +1012,10 @@ def grpc_transport_name(self):
     def grpc_asyncio_transport_name(self):
         return self.name + "GrpcAsyncIOTransport"
 
+    @property
+    def rest_transport_name(self):
+        return self.name + "RestTransport"
+
     @property
     def has_lro(self) -> bool:
         """Return whether the service has a long-running method."""

gapic/templates/%namespace/%name_%version/%sub/services/%service/async_client.py.j2

@@ -30,6 +30,7 @@ from .transports.grpc_asyncio import {{ service.grpc_asyncio_transport_name }}
 from .client import {{ service.client_name }}
 
 
+{# TODO(yon-mg): handle rest transport async client interaction #}
 class {{ service.async_client_name }}:
     """{{ service.meta.doc|rst(width=72, indent=4) }}"""
 

gapic/templates/%namespace/%name_%version/%sub/services/%service/client.py.j2

@@ -30,8 +30,13 @@ from google.iam.v1 import policy_pb2 as policy  # type: ignore
 {% endif %}
 {% endfilter %}
 from .transports.base import {{ service.name }}Transport, DEFAULT_CLIENT_INFO
+{%- if 'grpc' in opts.transport %}
 from .transports.grpc import {{ service.grpc_transport_name }}
 from .transports.grpc_asyncio import {{ service.grpc_asyncio_transport_name }}
+{%- endif %}
+{%- if 'rest' in opts.transport %}
+from .transports.rest import {{ service.name }}RestTransport
+{%- endif %}
 
 
 class {{ service.client_name }}Meta(type):
@@ -42,8 +47,13 @@ class {{ service.client_name }}Meta(type):
     objects.
     """
     _transport_registry = OrderedDict()  # type: Dict[str, Type[{{ service.name }}Transport]]
+    {%- if 'grpc' in opts.transport %}
     _transport_registry['grpc'] = {{ service.grpc_transport_name }}
     _transport_registry['grpc_asyncio'] = {{ service.grpc_asyncio_transport_name }}
+    {%- endif %}
+    {%- if 'rest' in opts.transport %}
+    _transport_registry['rest'] = {{ service.name }}RestTransport
+    {%- endif %}
 
     def get_transport_class(cls,
             label: str = None,

gapic/templates/%namespace/%name_%version/%sub/services/%service/transports/__init__.py.j2

@@ -5,19 +5,34 @@ from collections import OrderedDict
 from typing import Dict, Type
 
 from .base import {{ service.name }}Transport
+{%- if 'grpc' in opts.transport %}
 from .grpc import {{ service.name }}GrpcTransport
 from .grpc_asyncio import {{ service.name }}GrpcAsyncIOTransport
+{%- endif %}
+{%- if 'rest' in opts.transport %}
+from .rest import {{ service.name }}RestTransport
+{%- endif %}
+
 
 
 # Compile a registry of transports.
 _transport_registry = OrderedDict()  # type: Dict[str, Type[{{ service.name }}Transport]]
+{%- if 'grpc' in opts.transport %}
 _transport_registry['grpc'] = {{ service.name }}GrpcTransport
 _transport_registry['grpc_asyncio'] = {{ service.name }}GrpcAsyncIOTransport
-
+{%- endif %}
+{%- if 'rest' in opts.transport %}
+_transport_registry['rest'] = {{ service.name }}RestTransport
+{%- endif %}
 
 __all__ = (
     '{{ service.name }}Transport',
+    {%- if 'grpc' in opts.transport %}
     '{{ service.name }}GrpcTransport',
     '{{ service.name }}GrpcAsyncIOTransport',
+    {%- endif %}
+    {%- if 'rest' in opts.transport %}
+    '{{ service.name }}RestTransport',
+    {%- endif %}
 )
 {% endblock %}

gapic/templates/%namespace/%name_%version/%sub/services/%service/transports/grpc.py.j2

@@ -151,6 +151,9 @@ class {{ service.name }}GrpcTransport({{ service.name }}Transport):
             )
 
         self._stubs = {}  # type: Dict[str, Callable]
+        {%- if service.has_lro %}
+        self._operations_client = None
+        {%- endif %}
 
         # Run the base constructor.
         super().__init__(
@@ -172,7 +175,7 @@ class {{ service.name }}GrpcTransport({{ service.name }}Transport):
                        **kwargs) -> grpc.Channel:
         """Create and return a gRPC channel object.
         Args:
-            address (Optionsl[str]): The host for the channel to use.
+            address (Optional[str]): The host for the channel to use.
             credentials (Optional[~.Credentials]): The
                 authorization credentials to attach to requests. These
                 credentials identify this application to the service. If
@@ -220,13 +223,13 @@ class {{ service.name }}GrpcTransport({{ service.name }}Transport):
         client.
         """
         # Sanity check: Only create a new client if we do not already have one.
-        if 'operations_client' not in self.__dict__:
-            self.__dict__['operations_client'] = operations_v1.OperationsClient(
+        if self._operations_client is None:
+            self._operations_client = operations_v1.OperationsClient(
                 self.grpc_channel
             )
 
         # Return the client from cache.
-        return self.__dict__['operations_client']
+        return self._operations_client
     {%- endif %}
     {%- for method in service.methods.values() %}
 

gapic/templates/%namespace/%name_%version/%sub/services/%service/transports/grpc_asyncio.py.j2

@@ -205,6 +205,9 @@ class {{ service.grpc_asyncio_transport_name }}({{ service.name }}Transport):
         )
 
         self._stubs = {}
+        {%- if service.has_lro %}
+        self._operations_client = None
+        {%- endif %}
 
     @property
     def grpc_channel(self) -> aio.Channel:
@@ -225,13 +228,13 @@ class {{ service.grpc_asyncio_transport_name }}({{ service.name }}Transport):
         client.
         """
         # Sanity check: Only create a new client if we do not already have one.
-        if 'operations_client' not in self.__dict__:
-            self.__dict__['operations_client'] = operations_v1.OperationsAsyncClient(
+        if self._operations_client is None:
+            self._operations_client = operations_v1.OperationsAsyncClient(
                 self.grpc_channel
             )
 
         # Return the client from cache.
-        return self.__dict__['operations_client']
+        return self._operations_client
     {%- endif %}
     {%- for method in service.methods.values() %}