[Zope3-Users] Re: EditForm fails in SiteManager because of containment constraint

[Philipp von Weitershausen]

Hermann Himmelbauer wrote:
> Am Samstag, 7. April 2007 18:43 schrieb Christophe Combelles:
>> Jürgen Kartnaller a écrit :
>>> Christophe Combelles wrote:
>>>> Hello,
>>>>
>>>> I have a regular content object which uses the formlib for its edit
>>>> view. Nothing special, just like a Recipe.
>>>> But I want this object to only reside in the Site Manager, because it
>>>> will be used as a configurable local utility (some kind of
>>>> LocalKitchenTools utility)
>>>>
>>>> Everything is perfect, and the EditForm works well until I want to
>>>> tell this object to be only contained in the SiteManager. So I just
>>>> add this statement in the interface:
>>>>
>>>> containers(ILocalSiteManager)
>>>> or
>>>> containers(ISiteManagementFolder)
>>> 'container' adds __parent__ as schema.Field attribute to your interface.
>>> You need to omit __parent__ in your formlib form_fields definition.
>> thanks, that's it, so I will omit only __parent__
>> You had already answered while I was still writing my previous post :)
>>
>> Couldn't this thing be managed by the formlib itself?
>> The error is not explicit and does not mention __parent__ anywhere
> 
> Yes, this was also my problem - the error message was quite cryptic and it 
> took me hours to find out the reason.
> 
> A good solution would be to either making the error message more verbose, or 
> to automatically omit such attributes in the formlib (which could also lead 
> to other problems).

-1 on automatic exclusion, that would be a bit magical.

+1 on making the error message more verbose.

It shouldn't be a lot of work to adjust the setUpWidgets and 
setUpEditWidgets functions in zope.formlib.form to make 
queryMultiAdapter() calls instead of getMultiAdapter(). Then in case of 
a None return value (i.e. there's no widget), raise a WidgetLookupError 
(a subclass of LookupError) with a proper error message.

This is a small enough task that would make an excellent first 
contribution to Zope 3... any takers? :)

Steps you'd need to take:

* Become a Zope contributor by signing and mailing
   http://dev.zope.org/CVS/Contributor.pdf

* Write a test that exercises the desired behaviour, best by extending
   the zope.formlib/form.txt doctest. (We require automated tests for all
   modifications, especially for bugfixes and new features).

* Fix up zope.formlib.form to pass the test, in other words, introduce
   WidgetLookupError and raise it in the appropriate places.

* Check in the modifications.

All that should be done against the Zope 3 trunk. All in all it 
shouldn't take you more than half a day if you aren't familiar with 
Zope's source code yet, and it would open the door for future contributions.


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