[Zope-dev] zc.relationship - can't pickle module objects

[Martin Aspeli]

Gary Poster wrote:
> On Mar 16, 2009, at 4:02 AM, Martin Aspeli wrote:
> 
>> Hi,
>>
>> I *think* this is a bug in zc.relationship, but I'm not quite sure.
>>
>> I'm using ZODB3 3.8.1 (to get BLOB support) and trying to install
>> plone.app.relations, which depends on zc.relationship 1.0.2. In
>> particular, it  subclasses zc.relationship.shared.Container, and  
>> stores
>> a zc.relationship.index.Index object in self.relationIndex.
>>
>> Now, the __init__ of zc.relationship.index.Index, which derives from
>> Persistent, contains the code below. In self._relTools and and
>> self._attrs, there are a pile of modules, types and functions being
>> stored. I think these are causing the ZODB to barf. Interestingly,  
>> with
>> whatever version of ZODB that comes with Zope 2.10 (3.7?), there's no
>> problem.
>>
>> Any ideas how to work around this, or even why it's a problem in one
>> version of the ZODB but not another?
> 
> No idea yet.  What's the barf's traceback?

Mmmm... it seems that zc.relationship 1.1 fixes the issue, but has some 
other problems (an undefined variable minValues or similar - I haven't 
got a build with this version in it right now); 2.0dev seems better, 
albeit a bit scary at pre-alpha. Also, I think 2.0dev *requires* ZODB 
3.8, though, which means we have to choose one or the other. Ideally, 
I'd like a version of plone.relations that works with both ZODB 2.7 and 2.8.

I'm still having some problems with zc.relationship 2.0dev interacting 
with five.intid (which has some special path handling to aq-wrap objects 
that are turned from key references), though I'm hoping to work around them.

The traceback was:

    File
"/Users/optilude/.buildout/zope/Zope-2.10.6-final-py2.4/lib/python/ZServer/PubCore/ZServerPublisher.py", 

line 25, in __init__
      response=b)
    File
"/Users/optilude/.buildout/zope/Zope-2.10.6-final-py2.4/lib/python/ZPublisher/Publish.py", 

line 401, in publish_module
      environ, debug, request, response)
    File
"/Users/optilude/.buildout/zope/Zope-2.10.6-final-py2.4/lib/python/ZPublisher/Publish.py", 

line 202, in publish_module_standard
      response = publish(request, module_name, after_list, debug=debug)
    File
"/Users/optilude/.buildout/eggs/Products.PDBDebugMode-0.2-py2.4.egg/Products/PDBDebugMode/__init__.py", 

line 47, in pdb_publish
      mapply=mapply, )
    File
"/Users/optilude/.buildout/zope/Zope-2.10.6-final-py2.4/lib/python/ZPublisher/Publish.py", 

line 125, in publish
      transactions_manager.commit()
    File
"/Users/optilude/.buildout/zope/Zope-2.10.6-final-py2.4/lib/python/Zope2/App/startup.py", 

line 238, in commit
      transaction.commit()
    File
"/Users/optilude/.buildout/eggs/ZODB3-3.8.1-py2.4-macosx-10.3-i386.egg/transaction/_manager.py", 

line 93, in commit
      return self.get().commit()
    File
"/Users/optilude/.buildout/eggs/ZODB3-3.8.1-py2.4-macosx-10.3-i386.egg/transaction/_transaction.py", 

line 328, in commit
      t, v, tb = self._saveAndGetCommitishError()
    File
"/Users/optilude/.buildout/eggs/ZODB3-3.8.1-py2.4-macosx-10.3-i386.egg/transaction/_transaction.py", 

line 325, in commit
      self._commitResources()
    File
"/Users/optilude/.buildout/eggs/ZODB3-3.8.1-py2.4-macosx-10.3-i386.egg/transaction/_transaction.py", 

line 424, in _commitResources
      rm.commit(self)
    File
"/Users/optilude/.buildout/eggs/ZODB3-3.8.1-py2.4-macosx-10.3-i386.egg/ZODB/Connection.py", 

line 541, in commit
      self._commit(transaction)
    File
"/Users/optilude/.buildout/eggs/ZODB3-3.8.1-py2.4-macosx-10.3-i386.egg/ZODB/Connection.py", 

line 586, in _commit
      self._store_objects(ObjectWriter(obj), transaction)
    File
"/Users/optilude/.buildout/eggs/ZODB3-3.8.1-py2.4-macosx-10.3-i386.egg/ZODB/Connection.py", 

line 620, in _store_objects
      p = writer.serialize(obj)  # This calls __getstate__ of obj
    File
"/Users/optilude/.buildout/eggs/ZODB3-3.8.1-py2.4-macosx-10.3-i386.egg/ZODB/serialize.py", 

line 407, in serialize
      return self._dump(meta, obj.__getstate__())
    File
"/Users/optilude/.buildout/eggs/ZODB3-3.8.1-py2.4-macosx-10.3-i386.egg/ZODB/serialize.py", 

line 416, in _dump
      self._p.dump(state)
    File
"/opt/local/Library/Frameworks/Python.framework/Versions/2.4/lib/python2.4/copy_reg.py", 

line 69, in _reduce_ex
      raise TypeError, "can't pickle %s objects" % base.__name__
TypeError: can't pickle module objects

Martin

-- 
Author of `Professional Plone Development`, a book for developers who
want to work with Plone. See http://martinaspeli.net/plone-book