add test and fix bug

callback_row_query.go

@@ -23,6 +23,11 @@ type RowsQueryResult struct {
 func rowQueryCallback(scope *Scope) {
 	if result, ok := scope.InstanceGet("row_query_result"); ok {
 		scope.prepareQuerySQL()
+
+		if str, ok := scope.Get("gorm:query_hint"); ok {
+			scope.SQL = fmt.Sprint(str) + scope.SQL
+		}
+
 		if str, ok := scope.Get("gorm:query_option"); ok {
 			scope.SQL += addExtraSpaceIfExist(fmt.Sprint(str))
 		}

main_test.go

@@ -1262,6 +1262,17 @@ func TestCountWithQueryOption(t *testing.T) {
 	}
 }
 
+func TestQueryHint(t *testing.T) {
+	db := DB.New()
+	var count int
+
+	err := db.Set("gorm:query_hint", "/*master*/").Raw("select ?", "1").Count(&count).Error
+
+	if err != nil {
+		t.Error("Unexpected error on query_hint")
+	}
+}
+
 func TestFloatColumnPrecision(t *testing.T) {
 	if dialect := os.Getenv("GORM_DIALECT"); dialect != "mysql" && dialect != "sqlite" {
 		t.Skip()