Don't overwrite primary key if already it is already exist

callback_create.go

@@ -70,7 +70,7 @@ func Create(scope *Scope) {
 				id, err := result.LastInsertId()
 				if scope.Err(err) == nil {
 					scope.db.RowsAffected, _ = result.RowsAffected()
-					if primaryField != nil {
+					if primaryField != nil && primaryField.IsBlank {
 						scope.Err(scope.SetColumn(primaryField, id))
 					}
 				}

main_test.go

@@ -61,6 +61,18 @@ func init() {
 	runMigration()
 }
 
+func TestStringPrimaryKey(t *testing.T) {
+	type UUIDStruct struct {
+		ID   string `gorm:"primary_key"`
+		Name string
+	}
+
+	data := UUIDStruct{ID: "uuid", Name: "hello"}
+	if err := DB.Save(&data).Error; err != nil || data.ID != "uuid" {
+		t.Errorf("string primary key should not be populated")
+	}
+}
+
 func TestExceptionsWithInvalidSql(t *testing.T) {
 	var columns []string
 	if DB.Where("sdsd.zaaa = ?", "sd;;;aa").Pluck("aaa", &columns).Error == nil {