[Zope3-Users] Re: zalchemy integration

[Jürgen Kartnaller]

Hello Carlo.

The implementation of the container is more or less a demonstation on 
how to use sqlalchemy object together with a zope container.
To request an object for a zope container a name is used. In the case of 
sqlalchemy objects a generalization. This generalization make it 
possible to use any database table for the container. To have a unique 
name of the objects for the container I use the primary key.

This container implementation is (as you already noticed) not in use 
because all use cases we had until now use more special integrations.

Regards
Jürgen


Carlo Cardelli wrote:
> David Pratt wrote:
>> Hi Carlo.
>>
>> As a workaround to get objects into the db you can comment out the 
>> following lines in checkName like this:
>>
>>     def checkName(self, name, container):
>>         if isinstance(name, str):
>>             name = unicode(name)
>>         elif not isinstance(name, unicode):
>>             raise TypeError("Invalid name type", type(name))
>>
>>         #unproxied = removeSecurityProxy(container)
>>         #if not name.startswith(unproxied._class.__name__+'.'):
>>         #  raise UserError("Invalid name for SQLAlchemy object")
>>         return True
> 
> I actually worked around it as following:
> 
> <code>
>     unproxied = removeSecurityProxy(container)
> 
> ->      if not ISQLAlchemyContainer.providedBy(unproxied):
> ->          return NameChooser.checkName(self, name, container)
> 
>         if not name.startswith(unproxied._class.__name__ + '.'):
>             raise UserError("Invalid name for SQLAlchemy object")
> </code>
> 
> even if the 'else' case seems unused: i.e., this method is not called 
> while adding a SQLAlchemyContainer.
> 
> Once skipped this, the process halted while adding the 'blank' object to 
> the db: in zope.app.container.browser.adding, in the method add(), the 
> following lines failed:
> 
> <code>
>         container[name] = content
>         ... one ininfluent-for-this-problem line ...
>         return container[name]
> </code>
> 
> Here, the last line failed because the SQLAlchemyContainer completely 
> disregards the "name" attribute (as specified in container.txt), so 
> retrieving data using the same name is not possible.
> 
> Maybe I could spend some time in it, but this "basic" problem leads me 
> to some doubt about the state of the zalchemy package and its 
> integration with Zope3.
> 
> In the mailing list archives I found some discussion about ORM problems 
> (2-phase commit, thread support and so on) but nothing specific about 
> zalchemy, and (as far as I can see) no "definite" solution on the 
> sqlalchemy integration.
> 
> Could someone tell the current state-of-the-art about this, or his/her 
> experience about integrating sqlalchemy in other ways?
> 
> Thank you in advance.
> 
> Carlo Cardelli.