[Zope3-Users] Weird error for a certain named attribute

[Tom Dossis]

On 18/10/2007, at 11:58 PM, Maken Seteva wrote:

> Hello,
> I have a very strange error that I cannot understand. I get an  
> error for one of my attribute
> only when it is named a certain name!  It seems like there is an  
> old implementation of
> it that is haunting in the background, how is this possible?
>
> This cursed name is called "tags". This attribute is a list of  
> TextLine. I get the error when I
> don't add anything to the list in the adding view:
>
> "TypeError: iteration over non-sequence"
>
>
> However, if I rename the attribute to "wehoo" or really, anything  
> else, I don't get the TypeError and
> I can add my content object successfully (with an empty list for  
> wehoo). Here's my component:
>
> class IFoo(IContained):
> 	#...
>      tags = List(
>          title=_(u'Tags'),
>          description=_(u'A list of keywords'),
>          max_length=10,
>          value_type=TextLine(title=_(u'Tag')),
>          unique=True
>          )
> 	#...
>
>
> class Foo(Persistent):
> 	implements(IFoo)
> 	__name__ = __parent__ = None
> 	def __init__(self):
> 		#...
> 		self.tags = PersistentList()
> 		#...
>
> No custom widgets used for this field...
>
> I tried deleting all .pyc-files and deleting all old Foo objects,  
> and the site i run for testing followed by
> restarting the server. But adding new Foo objects still don't work.  
> (But renaming tags to anything else
> and then trying again will succeed).
>
> Any ideas?

Add: default=[] to your IFoo schema.

-Tom