Fix driver.Valuer interface returns nil, close #3248

schema/field.go

@@ -731,40 +731,10 @@ func (field *Field) setupValuerAndSetter() {
 				return nil
 			}
 		default:
-			if _, ok := fieldValue.Interface().(sql.Scanner); ok {
+			if _, ok := fieldValue.Elem().Interface().(sql.Scanner); ok {
-				// struct scanner
-				field.Set = func(value reflect.Value, v interface{}) (err error) {
-					if valuer, ok := v.(driver.Valuer); ok {
-						v, _ = valuer.Value()
-					}
-
-					reflectV := reflect.ValueOf(v)
-					if !reflectV.IsValid() {
-						field.ReflectValueOf(value).Set(reflect.New(field.FieldType).Elem())
-					} else if reflectV.Kind() == reflect.Ptr {
-						if reflectV.Elem().IsNil() || !reflectV.Elem().IsValid() {
-							field.ReflectValueOf(value).Set(reflect.New(field.FieldType).Elem())
-						} else {
-							return field.Set(value, reflectV.Elem().Interface())
-						}
-					} else {
-						err = field.ReflectValueOf(value).Addr().Interface().(sql.Scanner).Scan(v)
-					}
-					return
-				}
-			} else if _, ok := fieldValue.Elem().Interface().(sql.Scanner); ok {
 				// pointer scanner
 				field.Set = func(value reflect.Value, v interface{}) (err error) {
 					reflectV := reflect.ValueOf(v)
-
-					if valuer, ok := v.(driver.Valuer); ok {
-						if valuer == nil || reflectV.IsNil() {
-							field.ReflectValueOf(value).Set(reflect.New(field.FieldType).Elem())
-						} else {
-							v, _ = valuer.Value()
-						}
-					}
-
 					if reflectV.Type().AssignableTo(field.FieldType) {
 						field.ReflectValueOf(value).Set(reflectV)
 					} else if reflectV.Kind() == reflect.Ptr {
@@ -778,10 +748,38 @@ func (field *Field) setupValuerAndSetter() {
 						if fieldValue.IsNil() {
 							fieldValue.Set(reflect.New(field.FieldType.Elem()))
 						}
+
+						if valuer, ok := v.(driver.Valuer); ok {
+							v, _ = valuer.Value()
+						}
+
 						err = fieldValue.Interface().(sql.Scanner).Scan(v)
 					}
 					return
 				}
+			} else if _, ok := fieldValue.Interface().(sql.Scanner); ok {
+				// struct scanner
+				field.Set = func(value reflect.Value, v interface{}) (err error) {
+					reflectV := reflect.ValueOf(v)
+					if !reflectV.IsValid() {
+						field.ReflectValueOf(value).Set(reflect.New(field.FieldType).Elem())
+					} else if reflectV.Type().AssignableTo(field.FieldType) {
+						field.ReflectValueOf(value).Set(reflectV)
+					} else if reflectV.Kind() == reflect.Ptr {
+						if reflectV.IsNil() || !reflectV.IsValid() {
+							field.ReflectValueOf(value).Set(reflect.New(field.FieldType).Elem())
+						} else {
+							return field.Set(value, reflectV.Elem().Interface())
+						}
+					} else {
+						if valuer, ok := v.(driver.Valuer); ok {
+							v, _ = valuer.Value()
+						}
+
+						err = field.ReflectValueOf(value).Addr().Interface().(sql.Scanner).Scan(v)
+					}
+					return
+				}
 			} else {
 				field.Set = func(value reflect.Value, v interface{}) (err error) {
 					return fallbackSetter(value, v, field.Set)

tests/scanner_valuer_test.go

@@ -36,8 +36,8 @@ func TestScannerValuer(t *testing.T) {
 			{"name2", "value2"},
 		},
 		Role:             Role{Name: "admin"},
-		ExampleStruct:    ExampleStruct1{"name", "value"},
+		ExampleStruct:    ExampleStruct{"name", "value1"},
-		ExampleStructPtr: &ExampleStruct1{"name", "value"},
+		ExampleStructPtr: &ExampleStruct{"name", "value2"},
 	}
 
 	if err := DB.Create(&data).Error; err != nil {
@@ -46,19 +46,18 @@ func TestScannerValuer(t *testing.T) {
 
 	var result ScannerValuerStruct
 
-	if err := DB.Find(&result).Error; err != nil {
+	if err := DB.Find(&result, "id = ?", data.ID).Error; err != nil {
 		t.Fatalf("no error should happen when query scanner, valuer struct, but got %v", err)
 	}
 
+	if result.ExampleStructPtr.Val != "value2" {
+		t.Errorf(`ExampleStructPtr.Val should equal to "value2", but got %v`, result.ExampleStructPtr.Val)
+	}
+
+	if result.ExampleStruct.Val != "value1" {
+		t.Errorf(`ExampleStruct.Val should equal to "value1", but got %#v`, result.ExampleStruct)
+	}
 	AssertObjEqual(t, data, result, "Name", "Gender", "Age", "Male", "Height", "Birthday", "Password", "Bytes", "Num", "Strings", "Structs")
-
-	if result.ExampleStructPtr.Val != "value" {
-		t.Errorf(`ExampleStructPtr.Val should equal to "value", but got %v`, result.ExampleStructPtr.Val)
-	}
-
-	if result.ExampleStruct.Val != "value" {
-		t.Errorf(`ExampleStruct.Val should equal to "value", but got %v`, result.ExampleStruct.Val)
-	}
 }
 
 func TestScannerValuerWithFirstOrCreate(t *testing.T) {
@@ -71,6 +70,8 @@ func TestScannerValuerWithFirstOrCreate(t *testing.T) {
 		Name:             sql.NullString{String: "name", Valid: true},
 		Gender:           &sql.NullString{String: "M", Valid: true},
 		Age:              sql.NullInt64{Int64: 18, Valid: true},
+		ExampleStruct:    ExampleStruct{"name", "value1"},
+		ExampleStructPtr: &ExampleStruct{"name", "value2"},
 	}
 
 	var result ScannerValuerStruct
@@ -110,6 +111,8 @@ func TestInvalidValuer(t *testing.T) {
 
 	data := ScannerValuerStruct{
 		Password:         EncryptedData("xpass1"),
+		ExampleStruct:    ExampleStruct{"name", "value1"},
+		ExampleStructPtr: &ExampleStruct{"name", "value2"},
 	}
 
 	if err := DB.Create(&data).Error; err == nil {
@@ -149,8 +152,8 @@ type ScannerValuerStruct struct {
 	UserID           *sql.NullInt64
 	User             User
 	EmptyTime        EmptyTime
-	ExampleStruct    ExampleStruct1
+	ExampleStruct    ExampleStruct
-	ExampleStructPtr *ExampleStruct1
+	ExampleStructPtr *ExampleStruct
 }
 
 type EncryptedData []byte
@@ -216,24 +219,23 @@ func (l *StringsSlice) Scan(input interface{}) error {
 
 type ExampleStruct struct {
 	Name string
-	Value string
+	Val  string
 }
 
-type ExampleStruct1 struct {
+func (ExampleStruct) GormDataType() string {
-	Name  string `json:"name,omitempty"`
+	return "bytes"
-	Val   string `json:"val,omitempty"`
 }
 
-func (s ExampleStruct1) Value() (driver.Value, error) {
+func (s ExampleStruct) Value() (driver.Value, error) {
 	if len(s.Name) == 0 {
 		return nil, nil
 	}
-	//for test, has no practical meaning
+	// for test, has no practical meaning
 	s.Name = ""
 	return json.Marshal(s)
 }
 
-func (s *ExampleStruct1) Scan(src interface{}) error {
+func (s *ExampleStruct) Scan(src interface{}) error {
 	switch value := src.(type) {
 	case string:
 		return json.Unmarshal([]byte(value), s)