feat: form binding support encoding.TextUnmarshaler

binding/form_mapping.go

@@ -5,6 +5,7 @@
 package binding
 
 import (
+	"encoding"
 	"errors"
 	"fmt"
 	"reflect"
@@ -16,6 +17,11 @@ import (
 	"github.com/gin-gonic/gin/internal/json"
 )
 
+var (
+	typeTextUnmarshaler = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
+	typeTime            = reflect.TypeOf(time.Time{})
+)
+
 var errUnknownType = errors.New("unknown type")
 
 func mapUri(ptr interface{}, m map[string][]string) error {
@@ -205,11 +211,15 @@ func setWithProperType(val string, value reflect.Value, field reflect.StructFiel
 	case reflect.String:
 		value.SetString(val)
 	case reflect.Struct:
-		switch value.Interface().(type) {
+		tValue := value.Type()
-		case time.Time:
+		switch {
+		case tValue == typeTime:
 			return setTimeField(val, field, value)
+		case reflect.PtrTo(tValue).Implements(typeTextUnmarshaler):
+			return setTextUnmarshalerField(val, field, value.Addr())
+		default:
+			return json.Unmarshal(bytesconv.StringToBytes(val), value.Addr().Interface())
 		}
-		return json.Unmarshal(bytesconv.StringToBytes(val), value.Addr().Interface())
 	case reflect.Map:
 		return json.Unmarshal(bytesconv.StringToBytes(val), value.Addr().Interface())
 	default:
@@ -218,6 +228,11 @@ func setWithProperType(val string, value reflect.Value, field reflect.StructFiel
 	return nil
 }
 
+func setTextUnmarshalerField(val string, field reflect.StructField, value reflect.Value) error {
+	u := value.Interface().(encoding.TextUnmarshaler)
+	return u.UnmarshalText(bytesconv.StringToBytes(val))
+}
+
 func setIntField(val string, bitSize int, field reflect.Value) error {
 	if val == "" {
 		val = "0"

binding/form_mapping_test.go

@@ -5,6 +5,7 @@
 package binding
 
 import (
+	"github.com/gin-gonic/gin/internal/bytesconv"
 	"reflect"
 	"testing"
 	"time"
@@ -279,3 +280,43 @@ func TestMappingIgnoredCircularRef(t *testing.T) {
 	err := mappingByPtr(&s, formSource{}, "form")
 	assert.NoError(t, err)
 }
+
+type TestStringWrapper struct {
+	defined bool
+	val     string
+}
+
+func (t *TestStringWrapper) UnmarshalText(text []byte) error {
+	t.defined = true
+	t.val = bytesconv.BytesToString(text)
+	return nil
+}
+
+func (t *TestStringWrapper) String() string {
+	return t.val
+}
+
+func (t *TestStringWrapper) Undefined() bool {
+	return !t.defined
+}
+
+func TestMappingTextUnmarshaler(t *testing.T) {
+	type Query struct {
+		Name TestStringWrapper `json:"name" form:"name"`
+	}
+
+	q := Query{}
+	err := mappingByPtr(&q, formSource{}, "form")
+	assert.NoError(t, err)
+	assert.True(t, q.Name.Undefined())
+	assert.Empty(t, q.Name.String())
+
+	form := map[string][]string{
+		"name": {"test"},
+	}
+
+	err = mappingByPtr(&q, formSource(form), "form")
+	assert.NoError(t, err)
+	assert.False(t, q.Name.Undefined())
+	assert.Equal(t, "test", q.Name.String())
+}