Fix #216: Enable to call binding multiple times in some formats (#1341)

* Add interface to read body bytes in binding

* Add BindingBody implementation for some binding

* Fix to use `BindBodyBytesKey` for key

* Revert "Fix to use `BindBodyBytesKey` for key"

This reverts commit 2c82901ceab6ae53730a3cfcd9839bee11a08f13.

* Use private-like key for body bytes

* Add tests for BindingBody & ShouldBindBodyWith

* Add note for README

* Remove redundant space between sentences

binding/binding.go

@@ -29,6 +29,13 @@ type Binding interface {
 	Bind(*http.Request, interface{}) error
 }
 
+// BindingBody adds BindBody method to Binding. BindBody is similar with Bind,
+// but it reads the body from supplied bytes instead of req.Body.
+type BindingBody interface {
+	Binding
+	BindBody([]byte, interface{}) error
+}
+
 // StructValidator is the minimal interface which needs to be implemented in
 // order for it to be used as the validator engine for ensuring the correctness
 // of the reqest. Gin provides a default implementation for this using

binding/binding_body_test.go

@@ -0,0 +1,67 @@
+package binding
+
+import (
+	"bytes"
+	"io/ioutil"
+	"testing"
+
+	"github.com/gin-gonic/gin/binding/example"
+	"github.com/golang/protobuf/proto"
+	"github.com/stretchr/testify/assert"
+	"github.com/ugorji/go/codec"
+)
+
+func TestBindingBody(t *testing.T) {
+	for _, tt := range []struct {
+		name    string
+		binding BindingBody
+		body    string
+		want    string
+	}{
+		{
+			name:    "JSON bidning",
+			binding: JSON,
+			body:    `{"foo":"FOO"}`,
+		},
+		{
+			name:    "XML bidning",
+			binding: XML,
+			body: `<?xml version="1.0" encoding="UTF-8"?>
+<root>
+   <foo>FOO</foo>
+</root>`,
+		},
+		{
+			name:    "MsgPack binding",
+			binding: MsgPack,
+			body:    msgPackBody(t),
+		},
+	} {
+		t.Logf("testing: %s", tt.name)
+		req := requestWithBody("POST", "/", tt.body)
+		form := FooStruct{}
+		body, _ := ioutil.ReadAll(req.Body)
+		assert.NoError(t, tt.binding.BindBody(body, &form))
+		assert.Equal(t, FooStruct{"FOO"}, form)
+	}
+}
+
+func msgPackBody(t *testing.T) string {
+	test := FooStruct{"FOO"}
+	h := new(codec.MsgpackHandle)
+	buf := bytes.NewBuffer(nil)
+	assert.NoError(t, codec.NewEncoder(buf, h).Encode(test))
+	return buf.String()
+}
+
+func TestBindingBodyProto(t *testing.T) {
+	test := example.Test{
+		Label: proto.String("FOO"),
+	}
+	data, _ := proto.Marshal(&test)
+	req := requestWithBody("POST", "/", string(data))
+	form := example.Test{}
+	body, _ := ioutil.ReadAll(req.Body)
+	assert.NoError(t, ProtoBuf.BindBody(body, &form))
+	assert.Equal(t, test, form)
+}

binding/json.go

@@ -5,6 +5,8 @@
 package binding
 
 import (
+	"bytes"
+	"io"
 	"net/http"
 
 	"github.com/gin-gonic/gin/json"
@@ -22,7 +24,15 @@ func (jsonBinding) Name() string {
 }
 
 func (jsonBinding) Bind(req *http.Request, obj interface{}) error {
-	decoder := json.NewDecoder(req.Body)
+	return decodeJSON(req.Body, obj)
+}
+
+func (jsonBinding) BindBody(body []byte, obj interface{}) error {
+	return decodeJSON(bytes.NewReader(body), obj)
+}
+
+func decodeJSON(r io.Reader, obj interface{}) error {
+	decoder := json.NewDecoder(r)
 	if EnableDecoderUseNumber {
 		decoder.UseNumber()
 	}

binding/msgpack.go

@@ -5,6 +5,8 @@
 package binding
 
 import (
+	"bytes"
+	"io"
 	"net/http"
 
 	"github.com/ugorji/go/codec"
@@ -17,7 +19,16 @@ func (msgpackBinding) Name() string {
 }
 
 func (msgpackBinding) Bind(req *http.Request, obj interface{}) error {
-	if err := codec.NewDecoder(req.Body, new(codec.MsgpackHandle)).Decode(&obj); err != nil {
+	return decodeMsgPack(req.Body, obj)
+}
+
+func (msgpackBinding) BindBody(body []byte, obj interface{}) error {
+	return decodeMsgPack(bytes.NewReader(body), obj)
+}
+
+func decodeMsgPack(r io.Reader, obj interface{}) error {
+	cdc := new(codec.MsgpackHandle)
+	if err := codec.NewDecoder(r, cdc).Decode(&obj); err != nil {
 		return err
 	}
 	return validate(obj)

binding/protobuf.go

@@ -17,19 +17,20 @@ func (protobufBinding) Name() string {
 	return "protobuf"
 }
 
-func (protobufBinding) Bind(req *http.Request, obj interface{}) error {
-
+func (b protobufBinding) Bind(req *http.Request, obj interface{}) error {
 	buf, err := ioutil.ReadAll(req.Body)
 	if err != nil {
 		return err
 	}
+	return b.BindBody(buf, obj)
+}
 
-	if err = proto.Unmarshal(buf, obj.(proto.Message)); err != nil {
+func (protobufBinding) BindBody(body []byte, obj interface{}) error {
+	if err := proto.Unmarshal(body, obj.(proto.Message)); err != nil {
 		return err
 	}
-
-	//Here it's same to return validate(obj), but util now we cann't add `binding:""` to the struct
-	//which automatically generate by gen-proto
+	// Here it's same to return validate(obj), but util now we cann't add
+	// `binding:""` to the struct which automatically generate by gen-proto
 	return nil
-	//return validate(obj)
+	// return validate(obj)
 }

binding/xml.go

@@ -5,7 +5,9 @@
 package binding
 
 import (
+	"bytes"
 	"encoding/xml"
+	"io"
 	"net/http"
 )
 
@@ -16,7 +18,14 @@ func (xmlBinding) Name() string {
 }
 
 func (xmlBinding) Bind(req *http.Request, obj interface{}) error {
-	decoder := xml.NewDecoder(req.Body)
+	return decodeXML(req.Body, obj)
+}
+
+func (xmlBinding) BindBody(body []byte, obj interface{}) error {
+	return decodeXML(bytes.NewReader(body), obj)
+}
+func decodeXML(r io.Reader, obj interface{}) error {
+	decoder := xml.NewDecoder(r)
 	if err := decoder.Decode(obj); err != nil {
 		return err
 	}