Is it possible to set the end date relative to the selected start date in a D8 date range field? I have a date range field that I use to specify an accounting period. The end date should now be put to one year minus one day from the selected start date. For example, the start date 2016-07-01 will give the end date 2017-06-30. How is this possible?

1 Answer 1


The current widgets in core for the Datetime Range module do not allow this.

You would need to create a custom widget for this. Off the top of my head, I would create one that extends DateRangeWidgetBase() and mostly mirrors what DateRangeDefaultWidget() does, except to collect a relative period in a plain text field for the end date. Then, add a massageFormValues() function to turn the relative date into an absolute one, and then call parent::massageFormValues(). You may also be able to do this with a #process callback on the end date element, but I forget which of the two runs first during form processing.

  • And as a side note, if you get this working, it would be a great addition to the drupal.org/project/datetime_extras module if you post it as a patch.
    – mpdonadio
    Jun 12, 2018 at 0:16
  • And just altering the node form and adding a custom submit to populate the end field? Couldn't that work as well?
    – leymannx
    Jun 12, 2018 at 0:53
  • 1
    @leymannx The timestamp/datetime/daterange default widgets use HTML5 elements, which complicate matters. You also need to convert to a proper date before the massageFormValues (which tweaks the values for date-only and sets the storage time zone) and validation (which is at both the element and widget level) runs. This is messy in a node form alter. Doing this as a new field Widget is the easiest option.
    – mpdonadio
    Jun 12, 2018 at 0:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.