marshal_jsonpb: add check for slice sub types implementing proto.Message (#856)

* marshal_jsonpb: add check for slice sub types implementing proto.Message

* Added more tests.

Author: abice

examples/clients/responsebody/BUILD.bazel

@@ -15,6 +15,7 @@ go_library(
         "examplepb_response_body_out_response.go",
         "examplepb_response_body_req.go",
         "response_body_service_api.go",
+        "response_response_type.go",
     ],
     importpath = "github.com/grpc-ecosystem/grpc-gateway/examples/clients/responsebody",
     visibility = ["//visibility:public"],

examples/clients/responsebody/docs/ExamplepbRepeatedResponseBodyOutResponse.md

@@ -4,6 +4,7 @@
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **Data** | **string** |  | [optional] [default to null]
+**Type_** | [**ResponseResponseType**](ResponseResponseType.md) |  | [optional] [default to null]
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
 

examples/clients/responsebody/docs/ResponseResponseType.md

@@ -0,0 +1,9 @@
+# ResponseResponseType
+
+## Properties
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+
+[[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
+
+

examples/clients/responsebody/examplepb_repeated_response_body_out_response.go

@@ -13,4 +13,6 @@ package responsebody
 type ExamplepbRepeatedResponseBodyOutResponse struct {
 
 	Data string `json:"data,omitempty"`
+
+	Type_ ResponseResponseType `json:"type,omitempty"`
 }

examples/clients/responsebody/response_response_type.go

@@ -0,0 +1,14 @@
+/* 
+ * examples/proto/examplepb/response_body_service.proto
+ *
+ * No description provided (generated by Swagger Codegen https://github.com/swagger-api/swagger-codegen)
+ *
+ * OpenAPI spec version: version not set
+ * 
+ * Generated by: https://github.com/swagger-api/swagger-codegen.git
+ */
+
+package responsebody
+
+type ResponseResponseType struct {
+}

examples/integration/integration_test.go

@@ -1365,7 +1365,7 @@ func testResponseStrings(t *testing.T, port int) {
 	// Run Secondary server with different marshalling
 	ch := make(chan error)
 	go func() {
-		if err := runGateway(ctx, ":8081", runtime.WithMarshalerOption(runtime.MIMEWildcard, &runtime.JSONPb{EmitDefaults: true})); err != nil {
+		if err := runGateway(ctx, ":8081", runtime.WithMarshalerOption(runtime.MIMEWildcard, &runtime.JSONPb{EnumsAsInts: false, EmitDefaults: true})); err != nil {
 			ch <- fmt.Errorf("cannot run gateway service: %v", err)
 		}
 	}()
@@ -1387,6 +1387,11 @@ func testResponseStrings(t *testing.T, port int) {
 			expectedCode: http.StatusOK,
 			expectedBody: `[]`,
 		},
+		{
+			endpoint:     fmt.Sprintf("http://localhost:%d/responsebodies/foo", port),
+			expectedCode: http.StatusOK,
+			expectedBody: `[{"data":"foo","type":"UNKNOWN"}]`,
+		},
 	} {
 		t.Run(strconv.Itoa(i), func(t *testing.T) {
 			url := spec.endpoint

examples/proto/examplepb/response_body_service.pb.go

@@ -13,7 +13,18 @@ message ResponseBodyOut {
 }
 
 message RepeatedResponseBodyOut {
-  message Response { string data = 1; }
+  message Response {
+    string data = 1;
+    enum ResponseType {
+      // UNKNOWN
+      UNKNOWN = 0;
+      // A is 1
+      A = 1;
+      // B is 2
+      B = 2;
+    }
+    ResponseType type = 3;
+  }
   repeated Response response = 2;
 }
 

examples/proto/examplepb/response_body_service.proto

@@ -95,6 +95,16 @@
     }
   },
   "definitions": {
+    "ResponseResponseType": {
+      "type": "string",
+      "enum": [
+        "UNKNOWN",
+        "A",
+        "B"
+      ],
+      "default": "UNKNOWN",
+      "title": "- UNKNOWN: UNKNOWN\n - A: A is 1\n - B: B is 2"
+    },
     "examplepbRepeatedResponseBodyOut": {
       "type": "object",
       "properties": {
@@ -111,6 +121,9 @@
       "properties": {
         "data": {
           "type": "string"
+        },
+        "type": {
+          "$ref": "#/definitions/ResponseResponseType"
         }
       }
     },

examples/proto/examplepb/response_body_service.swagger.json

@@ -50,6 +50,11 @@ func (j *JSONPb) marshalTo(w io.Writer, v interface{}) error {
 	return (*jsonpb.Marshaler)(j).Marshal(w, p)
 }
 
+var (
+	// protoMessageType is stored to prevent constant lookup of the same type at runtime.
+	protoMessageType = reflect.TypeOf((*proto.Message)(nil)).Elem()
+)
+
 // marshalNonProto marshals a non-message field of a protobuf message.
 // This function does not correctly marshals arbitrary data structure into JSON,
 // but it is only capable of marshaling non-message field values of protobuf,
@@ -67,8 +72,38 @@ func (j *JSONPb) marshalNonProtoField(v interface{}) ([]byte, error) {
 		rv = rv.Elem()
 	}
 
-	if rv.Kind() == reflect.Slice && rv.IsNil() && j.EmitDefaults {
-		return []byte("[]"), nil
+	if rv.Kind() == reflect.Slice {
+		if rv.IsNil() {
+			if j.EmitDefaults {
+				return []byte("[]"), nil
+			}
+			return []byte("null"), nil
+		}
+
+		if rv.Type().Elem().Implements(protoMessageType) {
+			var buf bytes.Buffer
+			err := buf.WriteByte('[')
+			if err != nil {
+				return nil, err
+			}
+			for i := 0; i < rv.Len(); i++ {
+				if i != 0 {
+					err = buf.WriteByte(',')
+					if err != nil {
+						return nil, err
+					}
+				}
+				if err = (*jsonpb.Marshaler)(j).Marshal(&buf, rv.Index(i).Interface().(proto.Message)); err != nil {
+					return nil, err
+				}
+			}
+			err = buf.WriteByte(']')
+			if err != nil {
+				return nil, err
+			}
+
+			return buf.Bytes(), nil
+		}
 	}
 
 	if rv.Kind() == reflect.Map {