add jsonpb Render

context.go

@@ -23,6 +23,8 @@ import (
 	"github.com/gin-contrib/sse"
 	"github.com/gin-gonic/gin/binding"
 	"github.com/gin-gonic/gin/render"
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/proto"
 )
 
 // Content-Type MIME of the most common data formats.
@@ -939,6 +941,12 @@ func (c *Context) JSON(code int, obj interface{}) {
 	c.Render(code, render.JSON{Data: obj})
 }
 
+// JSONPB serializes the given proto Message as JSON into the response body.
+// It also sets the Content-Type as "application/json".
+func (c *Context) JSONPB(code int, obj proto.Message) {
+	c.Render(code, render.JSONPB{Data: obj, Option: protojson.MarshalOptions{EmitUnpopulated: true}})
+}
+
 // AsciiJSON serializes the given struct as JSON into the response body with unicode to ASCII string.
 // It also sets the Content-Type as "application/json".
 func (c *Context) AsciiJSON(code int, obj interface{}) {

render/jsonpb.go

@@ -0,0 +1,36 @@
+// Copyright 2014 Manu Martinez-Almeida.  All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+package render
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/proto"
+)
+
+// JSONPB contains the given proto.Message object.
+type JSONPB struct {
+	Data   proto.Message
+	datapb json.RawMessage
+	Option protojson.MarshalOptions
+}
+
+// Render (JSONPB) writes data with custom ContentType.
+func (r JSONPB) Render(w http.ResponseWriter) (err error) {
+	r.datapb, err = r.Option.Marshal(r.Data)
+	if err != nil {
+		return err
+	}
+	writeContentType(w, jsonContentType)
+	_, err = w.Write(r.datapb)
+	return err
+}
+
+// WriteContentType (JSON) writes JSON ContentType.
+func (r JSONPB) WriteContentType(w http.ResponseWriter) {
+	writeContentType(w, jsonContentType)
+}

render/render_test.go

@@ -15,7 +15,9 @@ import (
 	"testing"
 
 	testdata "github.com/gin-gonic/gin/testdata/protoexample"
+
 	"github.com/stretchr/testify/assert"
+	"google.golang.org/protobuf/encoding/protojson"
 	"google.golang.org/protobuf/proto"
 )
 
@@ -510,3 +512,46 @@ func TestRenderReaderNoContentLength(t *testing.T) {
 	assert.Equal(t, headers["Content-Disposition"], w.Header().Get("Content-Disposition"))
 	assert.Equal(t, headers["x-request-id"], w.Header().Get("x-request-id"))
 }
+
+func TestRenderJsonPb(t *testing.T) {
+	w := httptest.NewRecorder()
+	reps := []int64{int64(1), int64(2)}
+	typ := int32(11)
+	label := "test"
+	data := &testdata.Test{
+		Label:         &label,
+		Type:          &typ,
+		Reps:          reps,
+		Optionalgroup: &testdata.Test_OptionalGroup{RequiredField: &label},
+	}
+
+	r := (JSONPB{
+		Data:   data,
+		datapb: []byte{},
+		Option: protojson.MarshalOptions{
+			EmitUnpopulated: true,
+		},
+	})
+	r.WriteContentType(w)
+	result, err := protojson.MarshalOptions{EmitUnpopulated: true}.Marshal(data)
+	assert.NoError(t, err)
+	err = r.Render(w)
+	assert.NoError(t, err)
+	assert.Equal(t, string(result), w.Body.String())
+	assert.Equal(t, "application/json; charset=utf-8", w.Header().Get("Content-Type"))
+
+	w1 := httptest.NewRecorder()
+	r1 := (JSONPB{
+		Data:   nil,
+		datapb: []byte{},
+		Option: protojson.MarshalOptions{
+			EmitUnpopulated: true,
+		},
+	})
+	r1.WriteContentType(w)
+	result2 := "{}"
+	err1 := r1.Render(w1)
+	assert.NoError(t, err1)
+	assert.Equal(t, result2, w1.Body.String())
+	assert.Equal(t, "application/json; charset=utf-8", w1.Header().Get("Content-Type"))
+}