private async void save(object sender, EventArgs e) { var firstName = firstNameTextBox.Text; var lastName = lastNameTextBox.Text; var city = cityTextBox.Text; var address = addressTextBox.Text; var houseNumber = houseNumberTextBox.Text; var apartmentNumber = apartmentNumberTextBox.Text; var email = emailTextBox.Text; var password = passwordTextBox.Text; var password2 = passwordTextBox2.Text; if (checkCorrectness(firstName, lastName, city, address, houseNumber, apartmentNumber, email, password, password2)) { Account user = new Account(); user.firstName = firstName; user.lastName = lastName; user.city = city; user.address = address; user.houseNumber = houseNumber; user.apartmentNumber = apartmentNumber; user.email = email; user.password = password; await DatabaseService.insertUser(user).ContinueWith(task => { var result = task.Result; if (result) { MessageBox.Show("Rejestracja przebiegła pomyślnie."); if (InvokeRequired) { Invoke(new Action(() => Hide())); } else { Hide(); } } else { MessageBox.Show("Nie udało się zarejestrować użytkownika."); } }); } }