protected override ValidationResult IsValid(object value, ValidationContext validationContext) { TogelContext togelContext = new TogelContext(); if (value == null) { return(ValidationResult.Success); } string[] memberNames = new string[] { validationContext.MemberName }; var currentUser = validationContext.ObjectInstance as User; var user = togelContext.Users.ToList().Where(u => u.Name.ToLower() == value.ToString().ToLower() && u.UserID != currentUser.UserID).SingleOrDefault(); if (user == null) { return(ValidationResult.Success); } else { return(new ValidationResult("Sudah ada user dengan nama tersebut", memberNames)); } }