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