Don't overwrite existing timestamp when creating

callback_create.go

@@ -32,8 +32,18 @@ func beforeCreateCallback(scope *Scope) {
 func updateTimeStampForCreateCallback(scope *Scope) {
 	if !scope.HasError() {
 		now := NowFunc()
-		scope.SetColumn("CreatedAt", now)
-		scope.SetColumn("UpdatedAt", now)
+
+		if createdAtField, ok := scope.FieldByName("CreatedAt"); ok {
+			if createdAtField.IsBlank {
+				createdAtField.Set(now)
+			}
+		}
+
+		if updatedAtField, ok := scope.FieldByName("UpdatedAt"); ok {
+			if updatedAtField.IsBlank {
+				updatedAtField.Set(now)
+			}
+		}
 	}
 }
 

create_test.go

@@ -5,6 +5,8 @@ import (
 	"reflect"
 	"testing"
 	"time"
+
+	"github.com/jinzhu/now"
 )
 
 func TestCreate(t *testing.T) {
@@ -58,6 +60,34 @@ func TestCreate(t *testing.T) {
 	}
 }
 
+func TestCreateWithExistingTimestamp(t *testing.T) {
+	user := User{Name: "CreateUserExistingTimestamp"}
+
+	timeA := now.MustParse("2016-01-01")
+	user.CreatedAt = timeA
+	user.UpdatedAt = timeA
+	DB.Save(&user)
+
+	if user.CreatedAt.Format(time.RFC3339) != timeA.Format(time.RFC3339) {
+		t.Errorf("CreatedAt should not be changed")
+	}
+
+	if user.UpdatedAt.Format(time.RFC3339) != timeA.Format(time.RFC3339) {
+		t.Errorf("UpdatedAt should not be changed")
+	}
+
+	var newUser User
+	DB.First(&newUser, user.Id)
+
+	if newUser.CreatedAt.Format(time.RFC3339) != timeA.Format(time.RFC3339) {
+		t.Errorf("CreatedAt should not be changed")
+	}
+
+	if newUser.UpdatedAt.Format(time.RFC3339) != timeA.Format(time.RFC3339) {
+		t.Errorf("UpdatedAt should not be changed")
+	}
+}
+
 type AutoIncrementUser struct {
 	User
 	Sequence uint `gorm:"AUTO_INCREMENT"`