[Grok-dev] Problems rendering zope.schema.List

[Sebastian Ware]

I am trying some of the more interesting field types in zope.schema.  
I have added a List field to my interface IProtonObject...

   authors = schema.List(title=u'List of Authors', unique=True,  
value_type=schema.TextLine(title=u'Name'))

...but I get en error when I try to add the object...

   TypeError: iteration over non-sequence

...I use a simple add class:

   class Add(grok.AddForm):
     grok.context(ProtonCMS)
     form_fields = grok.Fields(id=schema.TextLine(title=u'id'))
     form_fields += grok.AutoFields(ProtonObject)

Traceback:

     return expression(self)
    - /Users/jhsware/GrokProjects/ProtonCMS/eggs/grok-0.9dev_r77371- 
py2.4.egg/grok/templates/default_edit_form.pt
    - Line 47, Column 12
    - Expression: <PathExpr standard:u'widget'>
   File "/local/zope3.3/lib/python/zope/tales/expressions.py", line  
217, in __call__
     return self._eval(econtext)
   File "/local/zope3.3/lib/python/zope/tales/expressions.py", line  
211, in _eval
     return ob()
   File "/local/zope3.3/lib/python/zope/app/form/browser/ 
sequencewidget.py", line 57, in __call__
     self._update()
   File "/local/zope3.3/lib/python/zope/app/form/browser/ 
sequencewidget.py", line 62, in _update
     sequence = self._getRenderedValue()
   File "/local/zope3.3/lib/python/zope/app/form/browser/ 
sequencewidget.py", line 128, in _getRenderedValue
     sequence = list(self._data)
TypeError: iteration over non-sequence

Mvh Sebastian