[Zope-dev] nasty persistence problem

[Michel Pelletier]

Tim McLaughlin wrote:
> 
> Thanks Chris, I'll hold on to that for a rainier day.  I just worked
> this one out in a very roundabout way ;)
> 
> A product had gotten copied in that moved a Product class from one
> module to another even though everything else was the same.  It seems
> that ZODB doesn't like that. 

It sure doesn't.  When it pickles an object, it says, here's a big
binary blob that is the state of the object.  The code for the object
can be found in Products.MyProduct.MyModule.MyClass.  When you move the
code, ZODB understandably barfs.

If I remember correctly, there is a way to make an alias in an old
location that points to a new location when you *must* move the code for
whatever reason.  I forget how it works though...

-Michel