Added protobuf support for negotiation

context.go

@@ -26,6 +26,7 @@ const (
 	MIMEHTML              = binding.MIMEHTML
 	MIMEXML               = binding.MIMEXML
 	MIMEXML2              = binding.MIMEXML2
+	MIMEPROTOBUF          = binding.MIMEPROTOBUF
 	MIMEPlain             = binding.MIMEPlain
 	MIMEPOSTForm          = binding.MIMEPOSTForm
 	MIMEMultipartPOSTForm = binding.MIMEMultipartPOSTForm
@@ -426,6 +427,12 @@ func (c *Context) XML(code int, obj interface{}) {
 	c.Render(code, render.XML{Data: obj})
 }
 
+// Protobuf serializes the given struct as PB binary-stream into response body
+// It also sets the Content-Type as "application/x-protobuf"
+func (c *Context) Protobuf(code int, obj interface{}) {
+	c.Render(code, render.Protobuf{Data: obj})
+}
+
 // String writes the given string into the response body.
 func (c *Context) String(code int, format string, values ...interface{}) {
 	c.Status(code)
@@ -489,6 +496,7 @@ type Negotiate struct {
 	HTMLData interface{}
 	JSONData interface{}
 	XMLData  interface{}
+	PBData   interface{}
 	Data     interface{}
 }
 
@@ -506,6 +514,10 @@ func (c *Context) Negotiate(code int, config Negotiate) {
 		data := chooseData(config.XMLData, config.Data)
 		c.XML(code, data)
 
+	case binding.MIMEPROTOBUF:
+		data := chooseData(config.PBData, config.Data)
+		c.Protobuf(code, data)
+
 	default:
 		c.AbortWithError(http.StatusNotAcceptable, errors.New("the accepted formats are not offered by the server"))
 	}

context_test.go

@@ -15,6 +15,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/gin-gonic/gin/binding/example"
+	"github.com/golang/protobuf/proto"
 	"github.com/manucorporat/sse"
 	"github.com/stretchr/testify/assert"
 )
@@ -374,6 +376,16 @@ func TestContextRenderXML(t *testing.T) {
 	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "application/xml; charset=utf-8")
 }
 
+// TestContextRenderProtobuf tests that the response is serialized as Protobuf binary-stream
+// and Content-Type is set to application/x-protobuf
+func TestContextRenderProtobuf(t *testing.T) {
+	c, w, _ := CreateTestContext()
+	c.Protobuf(201, &example.Test{Label: proto.String("test")})
+
+	assert.Equal(t, w.Code, 201)
+	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "application/x-protobuf")
+}
+
 // TestContextString tests that the response is returned
 // with Content-Type set to text/plain
 func TestContextRenderString(t *testing.T) {
@@ -500,15 +512,17 @@ func TestContextNegotiationFormat(t *testing.T) {
 	assert.Panics(t, func() { c.NegotiateFormat() })
 	assert.Equal(t, c.NegotiateFormat(MIMEJSON, MIMEXML), MIMEJSON)
 	assert.Equal(t, c.NegotiateFormat(MIMEHTML, MIMEJSON), MIMEHTML)
+	assert.Equal(t, c.NegotiateFormat(MIMEPROTOBUF, MIMEPROTOBUF), MIMEPROTOBUF)
 }
 
 func TestContextNegotiationFormatWithAccept(t *testing.T) {
 	c, _, _ := CreateTestContext()
 	c.Request, _ = http.NewRequest("POST", "/", nil)
-	c.Request.Header.Add("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8")
+	c.Request.Header.Add("Accept", "text/html,application/xhtml+xml,application/xml,application/x-protobuf;q=0.9,*/*;q=0.8")
 
 	assert.Equal(t, c.NegotiateFormat(MIMEJSON, MIMEXML), MIMEXML)
 	assert.Equal(t, c.NegotiateFormat(MIMEXML, MIMEHTML), MIMEHTML)
+	assert.Equal(t, c.NegotiateFormat(MIMEPROTOBUF, MIMEPROTOBUF), MIMEPROTOBUF)
 	assert.Equal(t, c.NegotiateFormat(MIMEJSON), "")
 }
 

render/protobuf.go

@@ -0,0 +1,24 @@
+package render
+
+import (
+	"github.com/golang/protobuf/proto"
+	"net/http"
+)
+
+type Protobuf struct {
+	Data interface{}
+}
+
+var pbContentType = []string{"application/x-protobuf"}
+
+func (r Protobuf) Render(w http.ResponseWriter) error {
+	writeContentType(w, pbContentType)
+	encoded, err := proto.Marshal(r.Data.(proto.Message))
+	if err != nil {
+		return err
+	}
+	if _, err = w.Write(encoded); err != nil {
+		return err
+	}
+	return nil
+}

render/render_test.go

@@ -10,6 +10,8 @@ import (
 	"net/http/httptest"
 	"testing"
 
+	"github.com/gin-gonic/gin/binding/example"
+	"github.com/golang/protobuf/proto"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -82,6 +84,19 @@ func TestRenderXML(t *testing.T) {
 	assert.Equal(t, w.Header().Get("Content-Type"), "application/xml; charset=utf-8")
 }
 
+func TestRenderProtobuf(t *testing.T) {
+	w := httptest.NewRecorder()
+	data := &example.Test{
+		Label: proto.String("test"),
+	}
+
+	err := (Protobuf{data}).Render(w)
+
+	assert.NoError(t, err)
+	// assert.Equal(t, w.Body.String(), "<map><foo>bar</foo></map>")
+	// assert.Equal(t, w.Header().Get("Content-Type"), "application/xml; charset=utf-8")
+}
+
 func TestRenderRedirect(t *testing.T) {
 	// TODO
 }