Fix set Scanner's data type

model_struct.go

@@ -194,7 +194,9 @@ func (scope *Scope) GetModelStruct() *ModelStruct {
 					if indirectType.Kind() == reflect.Struct {
 						for i := 0; i < indirectType.NumField(); i++ {
 							for key, value := range parseTagSetting(indirectType.Field(i).Tag) {
-								field.TagSettings[key] = value
+								if _, ok := field.TagSettings[key]; !ok {
+									field.TagSettings[key] = value
+								}
 							}
 						}
 					}

scaner_test.go

@@ -5,6 +5,8 @@ import (
 	"encoding/json"
 	"errors"
 	"testing"
+
+	"github.com/jinzhu/gorm"
 )
 
 func TestScannableSlices(t *testing.T) {
@@ -83,3 +85,53 @@ func (l *ExampleStructSlice) Scan(input interface{}) error {
 		return errors.New("not supported")
 	}
 }
+
+type ScannerDataType struct {
+	Street string `sql:"TYPE:varchar(24)"`
+}
+
+func (ScannerDataType) Value() (driver.Value, error) {
+	return nil, nil
+}
+
+func (*ScannerDataType) Scan(input interface{}) error {
+	return nil
+}
+
+type ScannerDataTypeTestStruct struct {
+	Field1          int
+	ScannerDataType *ScannerDataType `sql:"TYPE:json"`
+}
+
+type ScannerDataType2 struct {
+	Street string `sql:"TYPE:varchar(24)"`
+}
+
+func (ScannerDataType2) Value() (driver.Value, error) {
+	return nil, nil
+}
+
+func (*ScannerDataType2) Scan(input interface{}) error {
+	return nil
+}
+
+type ScannerDataTypeTestStruct2 struct {
+	Field1          int
+	ScannerDataType *ScannerDataType2
+}
+
+func TestScannerDataType(t *testing.T) {
+	scope := gorm.Scope{Value: &ScannerDataTypeTestStruct{}}
+	if field, ok := scope.FieldByName("ScannerDataType"); ok {
+		if DB.Dialect().DataTypeOf(field.StructField) != "json" {
+			t.Errorf("data type for scanner is wrong")
+		}
+	}
+
+	scope = gorm.Scope{Value: &ScannerDataTypeTestStruct2{}}
+	if field, ok := scope.FieldByName("ScannerDataType"); ok {
+		if DB.Dialect().DataTypeOf(field.StructField) != "varchar(24)" {
+			t.Errorf("data type for scanner is wrong")
+		}
+	}
+}