Fix embedded scanner/valuer, close #3283

schema/field.go

@@ -92,25 +92,30 @@ func (schema *Schema) ParseField(fieldStruct reflect.StructField) *Field {
 	valuer, isValuer := fieldValue.Interface().(driver.Valuer)
 	if isValuer {
 		if _, ok := fieldValue.Interface().(GormDataTypeInterface); !ok {
-			var overrideFieldValue bool
-			if v, err := valuer.Value(); v != nil && err == nil {
-				overrideFieldValue = true
+			if v, err := valuer.Value(); reflect.ValueOf(v).IsValid() && err == nil {
 				fieldValue = reflect.ValueOf(v)
 			}
 
-			if field.IndirectFieldType.Kind() == reflect.Struct {
-				for i := 0; i < field.IndirectFieldType.NumField(); i++ {
-					if !overrideFieldValue {
-						newFieldType := field.IndirectFieldType.Field(i).Type
+			var getRealFieldValue func(reflect.Value)
+			getRealFieldValue = func(v reflect.Value) {
+				rv := reflect.Indirect(v)
+				if rv.Kind() == reflect.Struct && !rv.Type().ConvertibleTo(reflect.TypeOf(time.Time{})) {
+					for i := 0; i < rv.Type().NumField(); i++ {
+						newFieldType := rv.Type().Field(i).Type
 						for newFieldType.Kind() == reflect.Ptr {
 							newFieldType = newFieldType.Elem()
 						}
 
 						fieldValue = reflect.New(newFieldType)
-						overrideFieldValue = true
+
+						if rv.Type() != reflect.Indirect(fieldValue).Type() {
+							getRealFieldValue(fieldValue)
+						}
+
+						if fieldValue.IsValid() {
+							return
 						}
 
-					// copy tag settings from valuer
 						for key, value := range ParseTagSetting(field.IndirectFieldType.Field(i).Tag.Get("gorm"), ";") {
 							if _, ok := field.TagSettings[key]; !ok {
 								field.TagSettings[key] = value
@@ -119,6 +124,9 @@ func (schema *Schema) ParseField(fieldStruct reflect.StructField) *Field {
 					}
 				}
 			}
+
+			getRealFieldValue(fieldValue)
+		}
 	}
 
 	if dbName, ok := field.TagSettings["COLUMN"]; ok {

tests/scanner_valuer_test.go

@@ -27,6 +27,7 @@ func TestScannerValuer(t *testing.T) {
 		Male:     sql.NullBool{Bool: true, Valid: true},
 		Height:   sql.NullFloat64{Float64: 1.8888, Valid: true},
 		Birthday: sql.NullTime{Time: time.Now(), Valid: true},
+		Allergen: NullString{sql.NullString{String: "Allergen", Valid: true}},
 		Password: EncryptedData("pass1"),
 		Bytes:    []byte("byte"),
 		Num:      18,
@@ -143,6 +144,7 @@ type ScannerValuerStruct struct {
 	Male             sql.NullBool
 	Height           sql.NullFloat64
 	Birthday         sql.NullTime
+	Allergen         NullString
 	Password         EncryptedData
 	Bytes            []byte
 	Num              Num
@@ -299,3 +301,7 @@ func (t *EmptyTime) Scan(v interface{}) error {
 func (t EmptyTime) Value() (driver.Value, error) {
 	return time.Now() /* pass tests, mysql 8 doesn't support 0000-00-00 by default */, nil
 }
+
+type NullString struct {
+	sql.NullString
+}