[html-formfu] Validation callback

[Ronald J Kimball]

Dermot wrote:

> I am trying to validate an item in a Select field. The field is
> populated with the first entry as a [0, 'Select a User'] option. I
> want to ensure that the user has not forgotten to make a selection
> from this Select field and that the Selection is valid. However I am
> struggling to get a validation::callback in config to work.

Have you considered having the first entry be ['', 'Select a User'] and 
simply using the Required constraint?

Ronald