support message and field options. (#334)

cmd/protoc-gen-openapi/examples/tests/openapiv3annotations/message.proto

@@ -82,6 +82,15 @@ service Messaging2 {
 }
 
 message Message {
+  option (openapi.v3.schema) = {
+    title: "This is an overridden message schema title";
+  };
+
   int64 id = 1;
-  string label = 2;
+  string label = 2 [
+    (openapi.v3.property) = {
+      title: "this is an overriden field schema title";
+      max_length: 255;
+    }
+  ];
 }

cmd/protoc-gen-openapi/examples/tests/openapiv3annotations/openapi.yaml

@@ -57,12 +57,15 @@ components:
             additionalProperties: true
             description: Contains an arbitrary serialized message along with a @type that describes the type of the serialized message.
         Message:
+            title: This is an overridden message schema title
             type: object
             properties:
                 id:
                     type: integer
                     format: int64
                 label:
+                    title: this is an overriden field schema title
+                    maxLength: 255
                     type: string
         Status:
             type: object

cmd/protoc-gen-openapi/examples/tests/openapiv3annotations/openapi_default_response.yaml

@@ -57,12 +57,15 @@ components:
             additionalProperties: true
             description: Contains an arbitrary serialized message along with a @type that describes the type of the serialized message.
         Message:
+            title: This is an overridden message schema title
             type: object
             properties:
                 id:
                     type: integer
                     format: int64
                 label:
+                    title: this is an overriden field schema title
+                    maxLength: 255
                     type: string
         Status:
             type: object

cmd/protoc-gen-openapi/examples/tests/openapiv3annotations/openapi_fq_schema_naming.yaml

@@ -73,12 +73,15 @@ components:
                     description: A list of messages that carry the error details.  There is a common set of message types for APIs to use.
             description: 'The `Status` type defines a logical error model that is suitable for different programming environments, including REST APIs and RPC APIs. It is used by [gRPC](https://github.com/grpc). Each `Status` message contains three pieces of data: error code, error message, and error details. You can find out more about this error model and how to work with it in the [API Design Guide](https://cloud.google.com/apis/design/errors).'
         tests.openapiv3annotations.message.v1.Message:
+            title: This is an overridden message schema title
             type: object
             properties:
                 id:
                     type: integer
                     format: int64
                 label:
+                    title: this is an overriden field schema title
+                    maxLength: 255
                     type: string
     securitySchemes:
         BasicAuth:

cmd/protoc-gen-openapi/examples/tests/openapiv3annotations/openapi_json.yaml

@@ -57,12 +57,15 @@ components:
             additionalProperties: true
             description: Contains an arbitrary serialized message along with a @type that describes the type of the serialized message.
         Message:
+            title: This is an overridden message schema title
             type: object
             properties:
                 id:
                     type: integer
                     format: int64
                 label:
+                    title: this is an overriden field schema title
+                    maxLength: 255
                     type: string
         Status:
             type: object

cmd/protoc-gen-openapi/examples/tests/openapiv3annotations/openapi_string_enum.yaml

@@ -57,12 +57,15 @@ components:
             additionalProperties: true
             description: Contains an arbitrary serialized message along with a @type that describes the type of the serialized message.
         Message:
+            title: This is an overridden message schema title
             type: object
             properties:
                 id:
                     type: integer
                     format: int64
                 label:
+                    title: this is an overriden field schema title
+                    maxLength: 255
                     type: string
         Status:
             type: object

cmd/protoc-gen-openapi/generator/generator.go

@@ -795,6 +795,12 @@ func (g *OpenAPIv3Generator) addSchemasForMessagesToDocumentV3(d *v3.Document, m
 				if inputOnly {
 					schema.Schema.WriteOnly = true
 				}
+
+				// Merge any `Property` annotations with the current
+				extProperty := proto.GetExtension(field.Desc.Options(), v3.E_Property)
+				if extProperty != nil {
+					proto.Merge(schema.Schema, extProperty.(*v3.Schema))
+				}
 			}
 
 			definitionProperties.AdditionalProperties = append(
@@ -806,17 +812,25 @@ func (g *OpenAPIv3Generator) addSchemasForMessagesToDocumentV3(d *v3.Document, m
 			)
 		}
 
+		schema := &v3.Schema{
+			Type:        "object",
+			Description: messageDescription,
+			Properties:  definitionProperties,
+			Required:    required,
+		}
+
+		// Merge any `Schema` annotations with the current
+		extSchema := proto.GetExtension(message.Desc.Options(), v3.E_Schema)
+		if extSchema != nil {
+			proto.Merge(schema, extSchema.(*v3.Schema))
+		}
+
 		// Add the schema to the components.schema list.
 		g.addSchemaToDocumentV3(d, &v3.NamedSchemaOrReference{
 			Name: schemaName,
 			Value: &v3.SchemaOrReference{
 				Oneof: &v3.SchemaOrReference_Schema{
-					Schema: &v3.Schema{
-						Type:        "object",
-						Description: messageDescription,
-						Properties:  definitionProperties,
-						Required:    required,
-					},
+					Schema: schema,
 				},
 			},
 		})

openapiv3/annotations.proto

@@ -49,4 +49,12 @@ extend google.protobuf.FileOptions {
 
 extend google.protobuf.MethodOptions {
   Operation operation = 1042;
+}
+
+extend google.protobuf.MessageOptions {
+  Schema schema = 1042;
+}
+
+extend google.protobuf.FieldOptions {
+  Schema property = 1042;
 }