Investigate the feedback about the new validation behavior [2 days]

[vursen]

Let's inquire into the feedback we got about the new validation behavior to find out whether there are any issues that need to be fixed before enabling this behavior by default.

• Entering invalid value to DatePicker does not show DatePicker as invalid in browser #1158 (comment)

Related to vaadin/platform#3066

[vursen]

Confirmed that date-picker has at least one issue with committing an invalid input when autoOpenDisabled. Created a ticket: vaadin/web-components#5066

[knoobie]

I don't have time to test it properly, but an idea to be tested that it works:

• You have a bean with a date property
• You register the bean with a binder (using setBean) and mark this date field as required
• User types a proper date and presses a save button: Expectation the server side date is stored and validation is successful
• User changes the date to something unparseable like "Lorem" and presses save again: Expectation client side validation is failing AND the server side (already stored) representation is nulled so that the bean is also invalid

Edit: the required state is just an example for a server validation. A more real example is probably a range validation on the server where the user has to be 18-100 years. If the validation of the server isn't called with the nulled value the second time, it didn't know that the user changed something in the UI - even tho the UI shows an error from the client side validation

[vursen]

Thank you @knoobie for your input.

I tested DatePicker + Binder with this snippet today:

public static class Bean {
  private LocalDate value;

  public LocalDate getValue() {
      return value;
  }

  public void setValue(LocalDate value) {
      this.value = value;
  }
}

public DatePickerView() {
  Div value = new Div();

  DatePicker datePicker = new DatePicker("DatePicker");
  // datePicker.setAutoOpen(false);

  Binder<Bean> binder = new Binder<>(Bean.class);
  binder.forField(datePicker)
          .withValidator(date -> date.equals(LocalDate.of(2022, 1, 1)),
                  "Unexpected value")
          .withValidationStatusHandler(status -> {
              value.setText("Binder Value: " + status.getField().getValue());
          })
          .bind("property");

  Bean bean = new Bean();
  bean.setValue(LocalDate.of(2022, 1, 1));
  binder.setBean(bean);

  add(datePicker, value);
}

which confirmed that the value is correctly reset to null and the binder is properly notified both as long as autoOpen is true. When I set autoOpen to false, the value isn't reset and therefore the binder isn't notified either. This is all the same issue that was reported above.

[knoobie]

Perfect! Thanks for confirmation!

[vursen]

Closing as vaadin/web-components#5066 was fixed.