Datetime input does not display value correctly

[ediathome]

Just tried to add a datetime field to one of my forms. When showing a edit form, the datetime value is not correctly set in the html value attribute. Example:

field(:begins_at).datetime

becomes:
<input id="exam_begins_at" name="exam[begins_at]" type="datetime-local" value="2025-12-05 19:56:00 UTC" class="form-control">

The value attribute is set to '2025-12-05 19:56:00 UTC' but it should be in the form of '2025-12-06T19:56:00.01' with no timezone given (as specified here). In Safari, Firefox and Chrome this value is not accepted.

I solved the problem by setting the value manually using the DateTime strftime method:

field(:begins_at).datetime(value: model.begins_at.strftime('%FT%T'))

which becomes:

<input id="exam_begins_at" name="exam[begins_at]" type="datetime-local" value="2025-12-05T19:56:00" class="form-control">

This value attribute is accepted in Safari/FF and Chrome. I am not quite sure whether this can be implemented somewhere.

Cheers

Martin