[Zope] Re: Adding new _properties

29 Mar 2004

      Serg wrote:
...
I had product with below properties:
class easyArticle(SimpleItem.SimpleItem):
    _properties = (
        {'id':'author', 'type':'string', 'mode':'w'}
    )
...
I inputted some objects of this product.
Later I added some properties:
class easyArticle(SimpleItem.SimpleItem):
    _properties = (
        {'id':'author', 'type':'string', 'mode':'w'},
        {'id':'n1','type':'float', 'mode':'w'},
        {'id':'n2','type':'float', 'mode':'w'}
    )
...
After that, I cannt read old objects of this class. Zope write:
Site Error
An error was encountered while publishing this resource.
Error Type: AttributeError
Error Value: n1
How can I solve this problem?
Two possibilities:

1) Create an update-method, which you call on each object and which adds the
required attribute (self.n1=0.0 etc.)

2) Add the additional (better: all) properties as class-attributes.

Something like:

   class easyArticle(SimpleItem.SimpleItem):
       id=''
       n1=0.0
       n2=0.0
       _properties = ...

Cheers, Maik

[Zope] Re: Adding new _properties

Maik Jablonski