Date Webform element fails validation

[ekes]

This for sure effects when the Webform element is used in a composite, it might also be the case with other uses. So 'to reproduce' place a LocalGov Forms Date or Date of Birth element in a composite, and then place the composite on a form. It will always produce a validation error.

Reason

The base class has a preValidationCallback that sets the input value of the element including the DateTime object in the #value https://git.drupalcode.org/project/webform/-/blob/6.2.x/src/Plugin/WebformElement/DateBase.php?ref_type=heads#L511
This is not done for the inherited version of the WebformElement in LocalGov Forms because https://git.drupalcode.org/project/webform/-/blob/6.2.x/src/Plugin/WebformElement/DateBase.php?ref_type=heads#L500 $element['type'] is localgov_forms_date or localgov_forms_dob and they're not in the lookup array https://git.drupalcode.org/project/webform/-/blob/6.2.x/src/Plugin/WebformElement/DateBase.php?ref_type=heads#L490 (oh look it says it's a workaround*).

Putting the datetime object on the INPUT value on the form (not just the element value that is being passed around) is required because get the input https://git.drupalcode.org/project/drupal/-/blob/11.x/core/lib/Drupal/Core/Datetime/Element/Datelist.php?ref_type=heads#L294 and then looks for the object on it https://git.drupalcode.org/project/drupal/-/blob/11.x/core/lib/Drupal/Core/Datetime/Element/Datelist.php?ref_type=heads#L316 oh because core.

Solution

I'm going to think for a bit. But best I have at the moment is to implement the preValidationCallback on our class.

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* RANT: Have I ever mentioned the way core date time element uses the date object for everything sucks: because seconds, because day without time, because of timezones, because it's stupid