[Zope] Products and clases with new attributes

[Max M]

Antonio Beamud Montero wrote:

> Long time ago I started to develop a big product, it's under development
> now, but with some stable releases in a client. My problem is that new
> releases of a Product adds new attributes and when I upgrade de Product,
> I need to create another instance and recreate all the system, because
> old instances in the zobd haven't that attributes...
> Now, it's no problem, but when this system is in production, with
> hundred of objects... buff... How I can solve this problem...?

####################
# put this external method in the root

new_default_value = ''
objects = self.ZopeFind(self,
             obj_metatypes=['big_product'], search_sub=1)
for path, obj in objects:
     obj.newAttr = new_default_value

####################
If you are updating a lot of objects you should probably do partial 
commits along the way or it can be rather slow. You can do it like that

new_default_value = ''
objects = self.ZopeFind(self,
             obj_metatypes=['big_product'], search_sub=1)

transaction = get_transaction() # magical built in function
i = 0
for path, obj in objects:
     obj.newAttr = new_default_value
     if i != 0 and not i % 100: # partial commit for ever 100
         transaction.commit(1)
     i += 1

####################
# naturally you can generalize it a bit

def update(meta_type, updater):
     """
     Finds all the objects, sub-commits and calls the updater function
     on every object
     """
     objects = self.ZopeFind(self, obj_metatypes=[meta_type],
                             search_sub=1)
     transaction = get_transaction() # magical built in function
     i = 0
     for path, obj in objects:
         updater(obj)
         if i != 0 and not i % 100: # partial commit for ever 100
             transaction.commit(1)
         i += 1


def updater(obj):
     "This updates the objects"
     new_default_value = ''
     obj.newAttr = new_default_value

update('big_product', updater)


regards Max M

 ><evolve>
   >    >