Fix for #1334

context.go

@@ -437,7 +437,7 @@ func (c *context) json(code int, i interface{}, indent string) error {
 		enc.SetIndent("", indent)
 	}
 	c.writeContentType(MIMEApplicationJSONCharsetUTF8)
-	c.response.WriteHeader(code)
+	c.response.Status = code
 	return enc.Encode(i)
 }
 

context_test.go

@@ -8,6 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"math"
 	"mime/multipart"
 	"net/http"
 	"net/http/httptest"
@@ -374,6 +375,34 @@ func TestContext(t *testing.T) {
 	assert.Equal(0, len(c.QueryParams()))
 }
 
+func TestContext_JSON_CommitsCustomResponseCode(t *testing.T) {
+	e := New()
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	rec := httptest.NewRecorder()
+	c := e.NewContext(req, rec).(*context)
+	err := c.JSON(http.StatusCreated, user{1, "Jon Snow"})
+
+	assert := testify.New(t)
+	if assert.NoError(err) {
+		assert.Equal(http.StatusCreated, rec.Code)
+		assert.Equal(MIMEApplicationJSONCharsetUTF8, rec.Header().Get(HeaderContentType))
+		assert.Equal(userJSON+"\n", rec.Body.String())
+	}
+}
+
+func TestContext_JSON_DoesntCommitResponseCodePrematurely(t *testing.T) {
+	e := New()
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	rec := httptest.NewRecorder()
+	c := e.NewContext(req, rec).(*context)
+	err := c.JSON(http.StatusCreated, map[string]float64{"a": math.NaN()})
+
+	assert := testify.New(t)
+	if assert.Error(err) {
+		assert.False(c.response.Committed)
+	}
+}
+
 func TestContextCookie(t *testing.T) {
 	e := New()
 	req := httptest.NewRequest(http.MethodGet, "/", nil)

response.go

@@ -67,7 +67,10 @@ func (r *Response) WriteHeader(code int) {
 // Write writes the data to the connection as part of an HTTP reply.
 func (r *Response) Write(b []byte) (n int, err error) {
 	if !r.Committed {
-		r.WriteHeader(http.StatusOK)
+		if r.Status == 0 {
+			r.Status = http.StatusOK
+		}
+		r.WriteHeader(r.Status)
 	}
 	n, err = r.Writer.Write(b)
 	r.Size += int64(n)

response_test.go

@@ -22,3 +22,22 @@ func TestResponse(t *testing.T) {
 	res.Write([]byte("test"))
 	assert.Equal(t, "echo", rec.Header().Get(HeaderServer))
 }
+
+func TestResponse_Write_FallsBackToDefaultStatus(t *testing.T) {
+	e := New()
+	rec := httptest.NewRecorder()
+	res := &Response{echo: e, Writer: rec}
+
+	res.Write([]byte("test"))
+	assert.Equal(t, http.StatusOK, rec.Code)
+}
+
+func TestResponse_Write_UsesSetResponseCode(t *testing.T) {
+	e := New()
+	rec := httptest.NewRecorder()
+	res := &Response{echo: e, Writer: rec}
+
+	res.Status = http.StatusBadRequest
+	res.Write([]byte("test"))
+	assert.Equal(t, http.StatusBadRequest, rec.Code)
+}