Hermann Himmelbauer wrote:
Am Donnerstag 28 August 2008 10:14:11 schrieb Martin Aspeli:
Marius Gedminas wrote:
On Wed, Aug 27, 2008 at 05:15:48PM -0700, Stephan Richter wrote:
On Wednesday 27 August 2008, Martin Aspeli wrote:
This means that if the request contains the empty-marker only (no selection was made) for a checkbox widget (say), then the return value is [], rather than default (NOVALUE).
Is that a bug? I have a custom checkbox widget derived from the standard checkbox widget, (z3c.formwidget.query, in fact), and I never get any "required missing" exceptions, even when I untick all the checkboxes and click OK.
Am I missing something? I think you have a point. Have you tried changing the behavior to return "default" and see what tests fail? If no major failures come out of this, I would say change it. Wait a second, maybe I'm misunderstanding this, but I certainly oppose any change that would make an unchecked checkbox an error during form validation.
A required Bool field can have two values: True or False. One is represented by a checked checkbox, the other by an unchecked checkbox. An unchecked checkbox is not missing input and should not trigger "required missing" errors. What about the case when you have a list of options of which you need to chose one or more? In that case, ticking none is a validation error.
Yes, in your case this should give a validation error. However, the case where someone uses a checkbox for a True/False operation is at least as common. And if "no ticking" gives a validation error, this would prevent using checkboxes for this case. Moreover, a checkbox is typically used to represent a "Bool" schema (by default it's a choice widget, I think), so that fits well, I think.
My suggestion would be to:
- Create some schema field, e.g. "MultipleChoice":
colors = MutlipleChoice(title='Colors', values=['red', 'green', 'blue'], default=['green', 'blue'], required=True)
- Register a widget for this field, which is then rendered as a bunch of checkboxes.
We already have such a field - it's an ICollection field with a Choice value_type. I suspect that we just need widget.SequenceWidget in z3c.form to have a special case for len(self.terms)==1, i.e. it's a checkbox with only one option, or maybe a special case for a BooleanField, or indeed have different widgets for Boolean and ICollection fields. Martin -- Author of `Professional Plone Development`, a book for developers who want to work with Plone. See http://martinaspeli.net/plone-book