feat(binding): add BindPlain (#3904)

* add BindPlain

* fix ci/cd error

binding/binding.go

@@ -84,6 +84,7 @@ var (
 	YAML          BindingBody = yamlBinding{}
 	Uri           BindingUri  = uriBinding{}
 	Header        Binding     = headerBinding{}
+	Plain         BindingBody = plainBinding{}
 	TOML          BindingBody = tomlBinding{}
 )
 

binding/binding_nomsgpack.go

@@ -81,6 +81,7 @@ var (
 	Uri           = uriBinding{}
 	Header        = headerBinding{}
 	TOML          = tomlBinding{}
+	Plain         = plainBinding{}
 )
 
 // Default returns the appropriate Binding instance based on the HTTP method

binding/binding_test.go

@@ -1342,6 +1342,46 @@ func (h hook) Read([]byte) (int, error) {
 	return 0, errors.New("error")
 }
 
+type failRead struct{}
+
+func (f *failRead) Read(b []byte) (n int, err error) {
+	return 0, errors.New("my fail")
+}
+
+func (f *failRead) Close() error {
+	return nil
+}
+
+func TestPlainBinding(t *testing.T) {
+	p := Plain
+	assert.Equal(t, "plain", p.Name())
+
+	var s string
+	req := requestWithBody("POST", "/", "test string")
+	assert.NoError(t, p.Bind(req, &s))
+	assert.Equal(t, s, "test string")
+
+	var bs []byte
+	req = requestWithBody("POST", "/", "test []byte")
+	assert.NoError(t, p.Bind(req, &bs))
+	assert.Equal(t, bs, []byte("test []byte"))
+
+	var i int
+	req = requestWithBody("POST", "/", "test fail")
+	assert.Error(t, p.Bind(req, &i))
+
+	req = requestWithBody("POST", "/", "")
+	req.Body = &failRead{}
+	assert.Error(t, p.Bind(req, &s))
+
+	req = requestWithBody("POST", "/", "")
+	assert.Nil(t, p.Bind(req, nil))
+
+	var ptr *string
+	req = requestWithBody("POST", "/", "")
+	assert.Nil(t, p.Bind(req, ptr))
+}
+
 func testProtoBodyBindingFail(t *testing.T, b Binding, name, path, badPath, body, badBody string) {
 	assert.Equal(t, name, b.Name())
 

binding/plain.go

@@ -0,0 +1,56 @@
+package binding
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"reflect"
+
+	"github.com/gin-gonic/gin/internal/bytesconv"
+)
+
+type plainBinding struct{}
+
+func (plainBinding) Name() string {
+	return "plain"
+}
+
+func (plainBinding) Bind(req *http.Request, obj interface{}) error {
+	all, err := io.ReadAll(req.Body)
+	if err != nil {
+		return err
+	}
+
+	return decodePlain(all, obj)
+}
+
+func (plainBinding) BindBody(body []byte, obj any) error {
+	return decodePlain(body, obj)
+}
+
+func decodePlain(data []byte, obj any) error {
+	if obj == nil {
+		return nil
+	}
+
+	v := reflect.ValueOf(obj)
+
+	for v.Kind() == reflect.Ptr {
+		if v.IsNil() {
+			return nil
+		}
+		v = v.Elem()
+	}
+
+	if v.Kind() == reflect.String {
+		v.SetString(bytesconv.BytesToString(data))
+		return nil
+	}
+
+	if _, ok := v.Interface().([]byte); ok {
+		v.SetBytes(data)
+		return nil
+	}
+
+	return fmt.Errorf("type (%T) unknown type", v)
+}