feat: add rest transport generation for clients with optional flag

gapic/generator/generator.py

@@ -275,9 +275,8 @@ def _render_template(
                         skip_subpackages
                         and service.meta.address.subpackage != api_schema.subpackage_view
                         or
-                        'grpc' in template_name and 'grpc' not in opts.transport
-                        or
-                        'rest' in template_name and 'rest' not in opts.transport
+                        'transport' in template_name
+                        and not self._is_desired_transport(template_name, opts)
                 ):
                     continue
 
@@ -297,6 +296,14 @@ 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
+        for transport in desired_transports:
+            if transport in template_name:
+                return True
+        return False
+
     def _get_file(
         self,
         template_name: str,

gapic/schema/wrappers.py

@@ -742,13 +742,14 @@ def field_headers(self) -> Sequence[str]:
     def http_opt(self) -> Dict[str, str]:
         """Return the http option for this method."""
         http = self.options.Extensions[annotations_pb2.http].ListFields()
+        answer: Dict[str, str] = None
         if len(http) < 1:
-            return None
+            return answer
 
         http_method = http[0]
-        answer: Dict[str, str] = {
-            'method':http_method[0].name,
-            'url':http_method[1],
+        answer = {
+            'method': http_method[0].name,
+            'url': http_method[1],
         }
         if len(http) > 1:
             http_opt = http[1]

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

@@ -107,10 +107,9 @@ class {{ service.name }}RestTransport({{ service.name }}Transport):
         # Return the client from cache.
         return self._operations_client
     {%- endif %}
-
-
     {%- for method in service.methods.values() %}
     {%- if method.http_opt %}
+
     def {{ method.name|snake_case }}(self,
             request: {{ method.input.ident }}, *,
             metadata: Sequence[Tuple[str, str]] = (),
@@ -162,11 +161,10 @@ class {{ service.name }}RestTransport({{ service.name }}Transport):
             {%- endif %}
         )
         {%- if not method.void %}
-        {%- endif %}
 
         # Return the response
         return {{ method.output.ident }}.from_json(response.content)
-        {%- else %}
+        {%- endif %}
     {%- endif %}
     {%- endfor %}
 

gapic/utils/options.py

@@ -40,8 +40,8 @@ class Options:
     lazy_import: bool = False
     old_naming: bool = False
     add_iam_methods: bool = False
-    # TODO(yonmg): should there be an enum for transport type?
-    transport: List[str] = None
+    # TODO(yon-mg): should there be an enum for transport type?
+    transport: List[str] = dataclasses.field(default_factory=lambda: [])
 
     # Class constants
     PYTHON_GAPIC_PREFIX: str = 'python-gapic-'
@@ -138,6 +138,7 @@ def tweak_path(p):
             lazy_import=bool(opts.pop('lazy-import', False)),
             old_naming=bool(opts.pop('old-naming', False)),
             add_iam_methods=bool(opts.pop('add-iam-methods', False)),
+            # transport should include desired transports delimited by '+', e.g. transport='grpc+rest'
             transport=opts.pop('transport', ['grpc'])[0].split('+')
         )