private void btnRegister_Click(object sender, EventArgs e) { User user = new User() { Name = this.txbRegisterName.Text, Surname = this.txbRegisterSurname.Text, Email = this.txbRegisterEmail.Text, Password = this.txbRegisterPassword.Text, Phone = this.txbRegisterPhone.Text, Type = (int)UserTypeEnum.User, }; bool isValid = ValidationOperation <User> .ValidateOperation(user); bool IsUnique = EmailValidation.IsUniqueEmail(user); if (IsUnique) { if (isValid) { UserDAL userDAL = new UserDAL(); userDAL.Add(user); MessageBox.Show("Successfully Registered!"); this.Close(); } } else { MessageBox.Show("The email is already used."); } }