Fix #198 (#781)

* Add new function to Render interface for writing content type only

* Add support for the new function in Render interface for writing content-type only

* Fix unhandled merge conflict in context_test.go

* Update vendor.json

context.go

@@ -17,7 +17,7 @@ import (
 
 	"github.com/gin-gonic/gin/binding"
 	"github.com/gin-gonic/gin/render"
-	"github.com/manucorporat/sse"
+	"gopkg.in/gin-contrib/sse.v0"
 )
 
 // Content-Type MIME of the most common data formats
@@ -405,6 +405,19 @@ func (c *Context) requestHeader(key string) string {
 /******** RESPONSE RENDERING ********/
 /************************************/
 
+// bodyAllowedForStatus is a copy of http.bodyAllowedForStatus non-exported function
+func bodyAllowedForStatus(status int) bool {
+	switch {
+	case status >= 100 && status <= 199:
+		return false
+	case status == 204:
+		return false
+	case status == 304:
+		return false
+	}
+	return true
+}
+
 func (c *Context) Status(code int) {
 	c.writermem.WriteHeader(code)
 }
@@ -454,6 +467,13 @@ func (c *Context) Cookie(name string) (string, error) {
 
 func (c *Context) Render(code int, r render.Render) {
 	c.Status(code)
+
+	if !bodyAllowedForStatus(code) {
+		r.WriteContentType(c.Writer)
+		c.Writer.WriteHeaderNow()
+		return
+	}
+
 	if err := r.Render(c.Writer); err != nil {
 		panic(err)
 	}
@@ -478,10 +498,7 @@ func (c *Context) IndentedJSON(code int, obj interface{}) {
 // JSON serializes the given struct as JSON into the response body.
 // It also sets the Content-Type as "application/json".
 func (c *Context) JSON(code int, obj interface{}) {
-	c.Status(code)
-	if err := render.WriteJSON(c.Writer, obj); err != nil {
-		panic(err)
-	}
+	c.Render(code, render.JSON{Data: obj})
 }
 
 // XML serializes the given struct as XML into the response body.
@@ -497,8 +514,7 @@ func (c *Context) YAML(code int, obj interface{}) {
 
 // String writes the given string into the response body.
 func (c *Context) String(code int, format string, values ...interface{}) {
-	c.Status(code)
-	render.WriteString(c.Writer, format, values)
+	c.Render(code, render.String{Format: format, Data: values})
 }
 
 // Redirect returns a HTTP redirect to the specific location.

context_test.go

@@ -7,6 +7,7 @@ package gin
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"html/template"
 	"mime/multipart"
 	"net/http"
@@ -15,9 +16,9 @@ import (
 	"testing"
 	"time"
 
-	"github.com/manucorporat/sse"
 	"github.com/stretchr/testify/assert"
 	"golang.org/x/net/context"
+	"gopkg.in/gin-contrib/sse.v0"
 )
 
 var _ context.Context = &Context{}
@@ -381,6 +382,35 @@ func TestContextGetCookie(t *testing.T) {
 	assert.Equal(t, cookie, "gin")
 }
 
+func TestContextBodyAllowedForStatus(t *testing.T) {
+	assert.Equal(t, false, bodyAllowedForStatus(102))
+	assert.Equal(t, false, bodyAllowedForStatus(204))
+	assert.Equal(t, false, bodyAllowedForStatus(304))
+	assert.Equal(t, true, bodyAllowedForStatus(500))
+}
+
+type TestPanicRender struct {
+}
+
+func (*TestPanicRender) Render(http.ResponseWriter) error {
+	return errors.New("TestPanicRender")
+}
+
+func (*TestPanicRender) WriteContentType(http.ResponseWriter) {}
+
+func TestContextRenderPanicIfErr(t *testing.T) {
+	defer func() {
+		r := recover()
+		assert.Equal(t, "TestPanicRender", fmt.Sprint(r))
+	}()
+	w := httptest.NewRecorder()
+	c, _ := CreateTestContext(w)
+
+	c.Render(http.StatusOK, &TestPanicRender{})
+
+	assert.Fail(t, "Panic not detected")
+}
+
 // Tests that the response is serialized as JSON
 // and Content-Type is set to application/json
 func TestContextRenderJSON(t *testing.T) {
@@ -394,6 +424,18 @@ func TestContextRenderJSON(t *testing.T) {
 	assert.Equal(t, "application/json; charset=utf-8", w.HeaderMap.Get("Content-Type"))
 }
 
+// Tests that no JSON is rendered if code is 204
+func TestContextRenderNoContentJSON(t *testing.T) {
+	w := httptest.NewRecorder()
+	c, _ := CreateTestContext(w)
+
+	c.JSON(204, H{"foo": "bar"})
+
+	assert.Equal(t, 204, w.Code)
+	assert.Equal(t, "", w.Body.String())
+	assert.Equal(t, "application/json; charset=utf-8", w.HeaderMap.Get("Content-Type"))
+}
+
 // Tests that the response is serialized as JSON
 // we change the content-type before
 func TestContextRenderAPIJSON(t *testing.T) {
@@ -408,6 +450,19 @@ func TestContextRenderAPIJSON(t *testing.T) {
 	assert.Equal(t, "application/vnd.api+json", w.HeaderMap.Get("Content-Type"))
 }
 
+// Tests that no Custom JSON is rendered if code is 204
+func TestContextRenderNoContentAPIJSON(t *testing.T) {
+	w := httptest.NewRecorder()
+	c, _ := CreateTestContext(w)
+
+	c.Header("Content-Type", "application/vnd.api+json")
+	c.JSON(204, H{"foo": "bar"})
+
+	assert.Equal(t, 204, w.Code)
+	assert.Equal(t, "", w.Body.String())
+	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "application/vnd.api+json")
+}
+
 // Tests that the response is serialized as JSON
 // and Content-Type is set to application/json
 func TestContextRenderIndentedJSON(t *testing.T) {
@@ -421,6 +476,18 @@ func TestContextRenderIndentedJSON(t *testing.T) {
 	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "application/json; charset=utf-8")
 }
 
+// Tests that no Custom JSON is rendered if code is 204
+func TestContextRenderNoContentIndentedJSON(t *testing.T) {
+	w := httptest.NewRecorder()
+	c, _ := CreateTestContext(w)
+
+	c.IndentedJSON(204, H{"foo": "bar", "bar": "foo", "nested": H{"foo": "bar"}})
+
+	assert.Equal(t, 204, w.Code)
+	assert.Equal(t, "", w.Body.String())
+	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "application/json; charset=utf-8")
+}
+
 // Tests that the response executes the templates
 // and responds with Content-Type set to text/html
 func TestContextRenderHTML(t *testing.T) {
@@ -436,6 +503,20 @@ func TestContextRenderHTML(t *testing.T) {
 	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "text/html; charset=utf-8")
 }
 
+// Tests that no HTML is rendered if code is 204
+func TestContextRenderNoContentHTML(t *testing.T) {
+	w := httptest.NewRecorder()
+	c, router := CreateTestContext(w)
+	templ := template.Must(template.New("t").Parse(`Hello {{.name}}`))
+	router.SetHTMLTemplate(templ)
+
+	c.HTML(204, "t", H{"name": "alexandernyquist"})
+
+	assert.Equal(t, 204, w.Code)
+	assert.Equal(t, "", w.Body.String())
+	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "text/html; charset=utf-8")
+}
+
 // TestContextXML tests that the response is serialized as XML
 // and Content-Type is set to application/xml
 func TestContextRenderXML(t *testing.T) {
@@ -449,6 +530,18 @@ func TestContextRenderXML(t *testing.T) {
 	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "application/xml; charset=utf-8")
 }
 
+// Tests that no XML is rendered if code is 204
+func TestContextRenderNoContentXML(t *testing.T) {
+	w := httptest.NewRecorder()
+	c, _ := CreateTestContext(w)
+
+	c.XML(204, H{"foo": "bar"})
+
+	assert.Equal(t, 204, w.Code)
+	assert.Equal(t, "", w.Body.String())
+	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "application/xml; charset=utf-8")
+}
+
 // TestContextString tests that the response is returned
 // with Content-Type set to text/plain
 func TestContextRenderString(t *testing.T) {
@@ -462,6 +555,18 @@ func TestContextRenderString(t *testing.T) {
 	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "text/plain; charset=utf-8")
 }
 
+// Tests that no String is rendered if code is 204
+func TestContextRenderNoContentString(t *testing.T) {
+	w := httptest.NewRecorder()
+	c, _ := CreateTestContext(w)
+
+	c.String(204, "test %s %d", "string", 2)
+
+	assert.Equal(t, 204, w.Code)
+	assert.Equal(t, "", w.Body.String())
+	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "text/plain; charset=utf-8")
+}
+
 // TestContextString tests that the response is returned
 // with Content-Type set to text/html
 func TestContextRenderHTMLString(t *testing.T) {
@@ -476,6 +581,19 @@ func TestContextRenderHTMLString(t *testing.T) {
 	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "text/html; charset=utf-8")
 }
 
+// Tests that no HTML String is rendered if code is 204
+func TestContextRenderNoContentHTMLString(t *testing.T) {
+	w := httptest.NewRecorder()
+	c, _ := CreateTestContext(w)
+
+	c.Header("Content-Type", "text/html; charset=utf-8")
+	c.String(204, "<html>%s %d</html>", "string", 3)
+
+	assert.Equal(t, 204, w.Code)
+	assert.Equal(t, "", w.Body.String())
+	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "text/html; charset=utf-8")
+}
+
 // TestContextData tests that the response can be written from `bytesting`
 // with specified MIME type
 func TestContextRenderData(t *testing.T) {
@@ -489,6 +607,18 @@ func TestContextRenderData(t *testing.T) {
 	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "text/csv")
 }
 
+// Tests that no Custom Data is rendered if code is 204
+func TestContextRenderNoContentData(t *testing.T) {
+	w := httptest.NewRecorder()
+	c, _ := CreateTestContext(w)
+
+	c.Data(204, "text/csv", []byte(`foo,bar`))
+
+	assert.Equal(t, 204, w.Code)
+	assert.Equal(t, "", w.Body.String())
+	assert.Equal(t, w.HeaderMap.Get("Content-Type"), "text/csv")
+}
+
 func TestContextRenderSSE(t *testing.T) {
 	w := httptest.NewRecorder()
 	c, _ := CreateTestContext(w)

middleware_test.go

@@ -10,8 +10,8 @@ import (
 
 	"testing"
 
-	"github.com/manucorporat/sse"
 	"github.com/stretchr/testify/assert"
+	"gopkg.in/gin-contrib/sse.v0"
 )
 
 func TestMiddlewareGeneralCase(t *testing.T) {

render/data.go

@@ -11,10 +11,13 @@ type Data struct {
 	Data        []byte
 }
 
-func (r Data) Render(w http.ResponseWriter) error {
-	if len(r.ContentType) > 0 {
-		w.Header()["Content-Type"] = []string{r.ContentType}
-	}
-	w.Write(r.Data)
-	return nil
+// Render (Data) writes data with custom ContentType
+func (r Data) Render(w http.ResponseWriter) (err error) {
+	r.WriteContentType(w)
+	_, err = w.Write(r.Data)
+	return
+}
+
+func (r Data) WriteContentType(w http.ResponseWriter) {
+	writeContentType(w, []string{r.ContentType})
 }

render/html.go

@@ -58,9 +58,14 @@ func (r HTMLDebug) loadTemplate() *template.Template {
 }
 
 func (r HTML) Render(w http.ResponseWriter) error {
-	writeContentType(w, htmlContentType)
+	r.WriteContentType(w)
+
 	if len(r.Name) == 0 {
 		return r.Template.Execute(w, r.Data)
 	}
 	return r.Template.ExecuteTemplate(w, r.Name, r.Data)
 }
+
+func (r HTML) WriteContentType(w http.ResponseWriter) {
+	writeContentType(w, htmlContentType)
+}

render/json.go

@@ -21,26 +21,37 @@ type (
 
 var jsonContentType = []string{"application/json; charset=utf-8"}
 
-func (r JSON) Render(w http.ResponseWriter) error {
-	return WriteJSON(w, r.Data)
+func (r JSON) Render(w http.ResponseWriter) (err error) {
+	if err = WriteJSON(w, r.Data); err != nil {
+		panic(err)
+	}
+	return
 }
 
-func (r IndentedJSON) Render(w http.ResponseWriter) error {
+func (r JSON) WriteContentType(w http.ResponseWriter) {
 	writeContentType(w, jsonContentType)
-	jsonBytes, err := json.MarshalIndent(r.Data, "", "    ")
+}
+
+func WriteJSON(w http.ResponseWriter, obj interface{}) error {
+	writeContentType(w, jsonContentType)
+	jsonBytes, err := json.Marshal(obj)
 	if err != nil {
 		return err
 	}
 	w.Write(jsonBytes)
 	return nil
 }
 
-func WriteJSON(w http.ResponseWriter, obj interface{}) error {
-	writeContentType(w, jsonContentType)
-	jsonBytes, err := json.Marshal(obj)
+func (r IndentedJSON) Render(w http.ResponseWriter) error {
+	r.WriteContentType(w)
+	jsonBytes, err := json.MarshalIndent(r.Data, "", "    ")
 	if err != nil {
 		return err
 	}
 	w.Write(jsonBytes)
 	return nil
 }
+
+func (r IndentedJSON) WriteContentType(w http.ResponseWriter) {
+	writeContentType(w, jsonContentType)
+}

render/redirect.go

@@ -22,3 +22,5 @@ func (r Redirect) Render(w http.ResponseWriter) error {
 	http.Redirect(w, r.Request, r.Location, r.Code)
 	return nil
 }
+
+func (r Redirect) WriteContentType(http.ResponseWriter) {}

render/render.go

@@ -8,6 +8,7 @@ import "net/http"
 
 type Render interface {
 	Render(http.ResponseWriter) error
+	WriteContentType(w http.ResponseWriter)
 }
 
 var (

render/text.go

@@ -22,9 +22,12 @@ func (r String) Render(w http.ResponseWriter) error {
 	return nil
 }
 
-func WriteString(w http.ResponseWriter, format string, data []interface{}) {
+func (r String) WriteContentType(w http.ResponseWriter) {
 	writeContentType(w, plainContentType)
+}
 
+func WriteString(w http.ResponseWriter, format string, data []interface{}) {
+	writeContentType(w, plainContentType)
 	if len(data) > 0 {
 		fmt.Fprintf(w, format, data...)
 	} else {