From 5036adbb9bb7127adf0f8d9cd7d34a70c24d634f Mon Sep 17 00:00:00 2001
From: chainhelen <chainhelen@gmail.com>
Date: Thu, 24 May 2018 23:14:34 -0400
Subject: [PATCH] Keep the logic of handling errors in render

---
 render/json.go        | 36 ++++++++++++++++++------------------
 render/redirect.go    |  3 ++-
 render/render_test.go | 10 ++++++----
 render/text.go        | 11 ++++++-----
 render/yaml.go        |  4 ++--
 5 files changed, 34 insertions(+), 30 deletions(-)

diff --git a/render/json.go b/render/json.go
index 3a2e8b2f..9983efa3 100755
--- a/render/json.go
+++ b/render/json.go
@@ -36,10 +36,7 @@ var jsonContentType = []string{"application/json; charset=utf-8"}
 var jsonpContentType = []string{"application/javascript; charset=utf-8"}
 
 func (r JSON) Render(w http.ResponseWriter) (err error) {
-	if err = WriteJSON(w, r.Data); err != nil {
-		panic(err)
-	}
-	return
+	return WriteJSON(w, r.Data)
 }
 
 func (r JSON) WriteContentType(w http.ResponseWriter) {
@@ -52,8 +49,8 @@ func WriteJSON(w http.ResponseWriter, obj interface{}) error {
 	if err != nil {
 		return err
 	}
-	w.Write(jsonBytes)
-	return nil
+	_, err = w.Write(jsonBytes)
+	return err
 }
 
 func (r IndentedJSON) Render(w http.ResponseWriter) error {
@@ -62,8 +59,8 @@ func (r IndentedJSON) Render(w http.ResponseWriter) error {
 	if err != nil {
 		return err
 	}
-	w.Write(jsonBytes)
-	return nil
+	_, err = w.Write(jsonBytes)
+	return err
 }
 
 func (r IndentedJSON) WriteContentType(w http.ResponseWriter) {
@@ -78,10 +75,10 @@ func (r SecureJSON) Render(w http.ResponseWriter) error {
 	}
 	// if the jsonBytes is array values
 	if bytes.HasPrefix(jsonBytes, []byte("[")) && bytes.HasSuffix(jsonBytes, []byte("]")) {
-		w.Write([]byte(r.Prefix))
+		jsonBytes = append([]byte(r.Prefix), jsonBytes...)
 	}
-	w.Write(jsonBytes)
-	return nil
+	_, err = w.Write(jsonBytes)
+	return err
 }
 
 func (r SecureJSON) WriteContentType(w http.ResponseWriter) {
@@ -96,17 +93,20 @@ func (r JsonpJSON) Render(w http.ResponseWriter) (err error) {
 	}
 
 	if r.Callback == "" {
-		w.Write(ret)
-		return nil
+		_, err := w.Write(ret)
+		return err
 	}
 
 	callback := template.JSEscapeString(r.Callback)
-	w.Write([]byte(callback))
-	w.Write([]byte("("))
-	w.Write(ret)
-	w.Write([]byte(")"))
 
-	return nil
+	tmp := []byte("")
+	tmp = append(tmp, []byte(callback)...)
+	tmp = append(tmp, []byte("(")...)
+	tmp = append(tmp, ret...)
+	tmp = append(tmp, []byte(")")...)
+
+	_, err = w.Write(tmp)
+	return err
 }
 
 func (r JsonpJSON) WriteContentType(w http.ResponseWriter) {
diff --git a/render/redirect.go b/render/redirect.go
index f874a351..53cc99f7 100644
--- a/render/redirect.go
+++ b/render/redirect.go
@@ -5,6 +5,7 @@
 package render
 
 import (
+	"errors"
 	"fmt"
 	"net/http"
 )
@@ -17,7 +18,7 @@ type Redirect struct {
 
 func (r Redirect) Render(w http.ResponseWriter) error {
 	if (r.Code < 300 || r.Code > 308) && r.Code != 201 {
-		panic(fmt.Sprintf("Cannot redirect with status code %d", r.Code))
+		return errors.New(fmt.Sprintf("Cannot redirect with status code %d", r.Code))
 	}
 	http.Redirect(w, r.Request, r.Location, r.Code)
 	return nil
diff --git a/render/render_test.go b/render/render_test.go
index 40ec806e..ebded478 100755
--- a/render/render_test.go
+++ b/render/render_test.go
@@ -62,12 +62,13 @@ func TestRenderJSON(t *testing.T) {
 	assert.Equal(t, "application/json; charset=utf-8", w.Header().Get("Content-Type"))
 }
 
-func TestRenderJSONPanics(t *testing.T) {
+func TestRenderJSONFail(t *testing.T) {
 	w := httptest.NewRecorder()
 	data := make(chan int)
 
 	// json: unsupported type: chan int
-	assert.Panics(t, func() { (JSON{data}).Render(w) })
+	err := (JSON{data}).Render(w)
+	assert.Error(t, err)
 }
 
 func TestRenderIndentedJSON(t *testing.T) {
@@ -84,7 +85,7 @@ func TestRenderIndentedJSON(t *testing.T) {
 	assert.Equal(t, "application/json; charset=utf-8", w.Header().Get("Content-Type"))
 }
 
-func TestRenderIndentedJSONPanics(t *testing.T) {
+func TestRenderIndentedJSONFail(t *testing.T) {
 	w := httptest.NewRecorder()
 	data := make(chan int)
 
@@ -258,7 +259,8 @@ func TestRenderRedirect(t *testing.T) {
 	}
 
 	w = httptest.NewRecorder()
-	assert.Panics(t, func() { data2.Render(w) })
+	err = data2.Render(w)
+	assert.Error(t, err)
 
 	// only improve coverage
 	data2.WriteContentType(w)
diff --git a/render/text.go b/render/text.go
index 74cd26be..e89f8583 100644
--- a/render/text.go
+++ b/render/text.go
@@ -18,19 +18,20 @@ type String struct {
 var plainContentType = []string{"text/plain; charset=utf-8"}
 
 func (r String) Render(w http.ResponseWriter) error {
-	WriteString(w, r.Format, r.Data)
-	return nil
+	return WriteString(w, r.Format, r.Data)
 }
 
 func (r String) WriteContentType(w http.ResponseWriter) {
 	writeContentType(w, plainContentType)
 }
 
-func WriteString(w http.ResponseWriter, format string, data []interface{}) {
+func WriteString(w http.ResponseWriter, format string, data []interface{}) error {
+	var err error
 	writeContentType(w, plainContentType)
 	if len(data) > 0 {
-		fmt.Fprintf(w, format, data...)
+		_, err = fmt.Fprintf(w, format, data...)
 	} else {
-		io.WriteString(w, format)
+		_, err = io.WriteString(w, format)
 	}
+	return err
 }
diff --git a/render/yaml.go b/render/yaml.go
index 25d0ebd4..0e242a19 100644
--- a/render/yaml.go
+++ b/render/yaml.go
@@ -24,8 +24,8 @@ func (r YAML) Render(w http.ResponseWriter) error {
 		return err
 	}
 
-	w.Write(bytes)
-	return nil
+	_, err = w.Write(bytes)
+	return err
 }
 
 func (r YAML) WriteContentType(w http.ResponseWriter) {