Allow custom JSON encoder (like jsoniter) (#105)

README.md

@@ -104,6 +104,9 @@ r := render.New(render.Options{
     HTMLTemplateOption: "missingkey=error", // Sets the option value for HTML templates. See https://pkg.go.dev/html/template#Template.Option for a list of known options.
     RequirePartials: true, // Return an error if a template is missing a partial used in a layout.
     DisableHTTPErrorRendering: true, // Disables automatic rendering of http.StatusInternalServerError when an error occurs.
+    JSONEncoder: func(w io.Writer) render.JSONEncoder { // Use jsoniter "github.com/json-iterator"
+        return jsoniter.NewEncoder(w)
+    },
 })
 // ...
 ~~~
@@ -146,6 +149,7 @@ r := render.New(render.Options{
     DisableHTTPErrorRendering: false,
     RenderPartialsWithoutPrefix: false,
     BufferPool: GenericBufferPool,
+    JSONEncoder: nil,
 })
 ~~~
 

engine.go

@@ -34,13 +34,21 @@ type HTML struct {
 	bp GenericBufferPool
 }
 
+// JSONEncoder match encoding/json.Encoder capabilities.
+type JSONEncoder interface {
+	Encode(v interface{}) error
+	SetEscapeHTML(on bool)
+	SetIndent(prefix, indent string)
+}
+
 // JSON built-in renderer.
 type JSON struct {
 	Head
 	Indent        bool
 	UnEscapeHTML  bool
 	Prefix        []byte
 	StreamingJSON bool
+	NewEncoder    func(w io.Writer) JSONEncoder
 }
 
 // JSONP built-in renderer.
@@ -114,7 +122,7 @@ func (j JSON) Render(w io.Writer, v interface{}) error {
 	}
 
 	var buf bytes.Buffer
-	encoder := json.NewEncoder(&buf)
+	encoder := j.NewEncoder(&buf)
 	encoder.SetEscapeHTML(!j.UnEscapeHTML)
 
 	if j.Indent {
@@ -155,7 +163,7 @@ func (j JSON) renderStreamingJSON(w io.Writer, v interface{}) error {
 		_, _ = w.Write(j.Prefix)
 	}
 
-	encoder := json.NewEncoder(w)
+	encoder := j.NewEncoder(w)
 	encoder.SetEscapeHTML(!j.UnEscapeHTML)
 
 	if j.Indent {

render.go

@@ -2,6 +2,7 @@ package render
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
 	"html/template"
 	"io"
@@ -117,6 +118,8 @@ type Options struct {
 	// BufferPool to use when rendering HTML templates. If none is supplied
 	// defaults to SizedBufferPool of size 32 with 512KiB buffers.
 	BufferPool GenericBufferPool
+	// Custom JSON Encoder. Default to encoding/json.NewEncoder.
+	JSONEncoder func(w io.Writer) JSONEncoder
 }
 
 // HTMLOptions is a struct for overriding some rendering Options for specific HTML call.
@@ -209,6 +212,12 @@ func (r *Render) prepareOptions() {
 	} else {
 		r.lock = &emptyLock{}
 	}
+
+	if r.opt.JSONEncoder == nil {
+		r.opt.JSONEncoder = func(w io.Writer) JSONEncoder {
+			return json.NewEncoder(w)
+		}
+	}
 }
 
 func (r *Render) CompileTemplates() {
@@ -526,6 +535,7 @@ func (r *Render) JSON(w io.Writer, status int, v interface{}) error {
 		Prefix:        r.opt.PrefixJSON,
 		UnEscapeHTML:  r.opt.UnEscapeHTML,
 		StreamingJSON: r.opt.StreamingJSON,
+		NewEncoder:    r.opt.JSONEncoder,
 	}
 
 	return r.Render(w, j, v)

render_json_test.go

@@ -2,6 +2,7 @@ package render
 
 import (
 	"encoding/json"
+	"io"
 	"math"
 	"net/http"
 	"net/http/httptest"
@@ -13,6 +14,28 @@ type Greeting struct {
 	Two string `json:"two"`
 }
 
+type TestEncoder struct {
+	JSONEncoder
+	w io.Writer
+}
+
+func (e TestEncoder) NewEncoder(w io.Writer) JSONEncoder {
+	return TestEncoder{w: w}
+}
+
+func (e TestEncoder) Encode(v interface{}) error {
+	e.w.Write([]byte(e.String()))
+	return nil
+}
+
+func (e TestEncoder) SetEscapeHTML(on bool) {}
+
+func (e TestEncoder) SetIndent(prefix, indent string) {}
+
+func (e TestEncoder) String() string {
+	return "{\"one\":\"world\",\"two\":\"hello\"}"
+}
+
 func TestJSONBasic(t *testing.T) {
 	render := New()
 
@@ -346,3 +369,46 @@ func TestJSONDisabledCharset(t *testing.T) {
 	expect(t, res.Header().Get(ContentType), ContentJSON)
 	expect(t, res.Body.String(), "{\"one\":\"hello\",\"two\":\"world\"}")
 }
+
+func TestJSONEncoder(t *testing.T) {
+	render := New(Options{
+		JSONEncoder: TestEncoder{}.NewEncoder,
+	})
+
+	var err error
+
+	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		err = render.JSON(w, 299, Greeting{"hello", "world"})
+	})
+
+	res := httptest.NewRecorder()
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, "/foo", nil)
+	h.ServeHTTP(res, req)
+
+	expectNil(t, err)
+	expect(t, res.Code, 299)
+	expect(t, res.Header().Get(ContentType), ContentJSON+"; charset=UTF-8")
+	expect(t, res.Body.String(), TestEncoder{}.String())
+}
+
+func TestJSONEncoderStream(t *testing.T) {
+	render := New(Options{
+		JSONEncoder:   TestEncoder{}.NewEncoder,
+		StreamingJSON: true,
+	})
+
+	var err error
+
+	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		err = render.JSON(w, 299, Greeting{"hello", "world"})
+	})
+
+	res := httptest.NewRecorder()
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, "/foo", nil)
+	h.ServeHTTP(res, req)
+
+	expectNil(t, err)
+	expect(t, res.Code, 299)
+	expect(t, res.Header().Get(ContentType), ContentJSON+"; charset=UTF-8")
+	expect(t, res.Body.String(), TestEncoder{}.String())
+}