ZODBBrowser can't handle some OrderedContainer subclasses

[Marius Gedminas]

From a mail by Thierry Florac:
> I've built a custom OrderedContainer subclass where _order is a
> PersistentList but where _data is an OOBTree.
>
> When trying to display such a class's instance in ZODBBrowser, I get a
> TypeError on "container._data.__setstate__(old_data_state)" (in
> state.py) with a bad arguments count ("TypeError: __setstate__() takes
> exactly 2 arguments (1 given)").

[Marius Gedminas (mgedmin)]

The time-limited-connection branch of ZODBBrowser ought to fix this.

[Thierry Florac (tflorac)]

Hi,
I made a new checkout of this branch and tried it (in a ZEO context, with ZODB-3.10.5).
I'm actually getting an IndexError on many (most !) pages...

Here is the traceback :

URL: /var/local/src/zodbbrowser-tlc/time-limited-connection/src/zodbbrowser/templates/zodbinfo.pt
File '/var/local/eggs/Paste-1.7.5.1-py2.6.egg/paste/evalexception/middleware.py', line 306 in respond
  app_iter = self.application(environ, detect_start_response)
File '/var/local/eggs/WebOb-1.2b2-py2.6.egg/webob/dec.py', line 132 in __call__
  resp = self.call_func(req, *args, **self.kwargs)
File '/var/local/eggs/WebOb-1.2b2-py2.6.egg/webob/dec.py', line 197 in call_func
  return self.func(req, *args, **kwargs)
File '/var/local/eggs/fanstatic-0.11.3-py2.6.egg/fanstatic/publisher.py', line 234 in __call__
  return request.get_response(self.app)
File '/var/local/eggs/WebOb-1.2b2-py2.6.egg/webob/request.py', line 1149 in get_response
  application, catch_exc_info=False)
File '/var/local/eggs/WebOb-1.2b2-py2.6.egg/webob/request.py', line 1118 in call_application
  app_iter = application(self.environ, start_response)
File '/var/local/eggs/WebOb-1.2b2-py2.6.egg/webob/dec.py', line 132 in __call__
  resp = self.call_func(req, *args, **self.kwargs)
File '/var/local/eggs/WebOb-1.2b2-py2.6.egg/webob/dec.py', line 197 in call_func
  return self.func(req, *args, **kwargs)
File '/var/local/eggs/fanstatic-0.11.3-py2.6.egg/fanstatic/injector.py', line 52 in __call__
  response = request.get_response(self.app)
File '/var/local/eggs/WebOb-1.2b2-py2.6.egg/webob/request.py', line 1149 in get_response
  application, catch_exc_info=False)
File '/var/local/eggs/WebOb-1.2b2-py2.6.egg/webob/request.py', line 1118 in call_application
  app_iter = application(self.environ, start_response)
File '/var/local/eggs/Paste-1.7.5.1-py2.6.egg/paste/translogger.py', line 68 in __call__
  return self.application(environ, replacement_start_response)
File '/var/local/env/ids/src/webapp/startup.py', line 32 in wrapper
  return app(environ, start_response)
File '/var/local/eggs/zope.app.wsgi-3.10.0-py2.6.egg/zope/app/wsgi/__init__.py', line 59 in __call__
  request = publish(request, handle_errors=handle_errors)
File '/var/local/eggs/zope.publisher-3.12.6-py2.6.egg/zope/publisher/publish.py', line 132 in publish
  result = publication.callObject(request, obj)
File '/var/local/eggs/zope.app.publication-3.12.0-py2.6.egg/zope/app/publication/zopepublication.py', line 207 in callObject
  return mapply(ob, request.getPositionalArguments(), request)
<bound method ZodbInfoView.__call__ of <zope.browserpage.metaconfigure.ZodbInfoView object at 0x6fe5c90>>
File '/var/local/eggs/zope.publisher-3.12.6-py2.6.egg/zope/publisher/publish.py', line 107 in mapply
  return debug_call(obj, args)
File '/var/local/eggs/zope.publisher-3.12.6-py2.6.egg/zope/publisher/publish.py', line 113 in debug_call
  return obj(*args)
File '/var/local/src/zodbbrowser-tlc/time-limited-connection/src/zodbbrowser/browser.py', line 91 in __call__
  return self.render()
File '/var/local/src/zodbbrowser-tlc/time-limited-connection/src/zodbbrowser/browser.py', line 149 in render
  return self.template()
File '/var/local/eggs/zope.browserpage-3.12.2-py...

[Marius Gedminas (mgedmin)]

Hm, I've seen that IndexError while I was testing, but I was sure I'd fixed it a week ago... :(

[Marius Gedminas (mgedmin)]

I've doubts about the viability of the approach taken in the time-limited-connection branch.

I would appreciate suggestions of how to handle custom OrderedContainer subclasses reliably, because I'm out of ideas.

The pragmatic thing would be to register custom IObjectHistory/IStateInterpeter adapters based on the existing ones in btreesupport.py. If you use zodbbrowser as a plugin to your Zope-ish project, this will be simple. If you use a standalone zodbbrowser, it'll be trickier -- you might need to fork it.

Or you could contribute a BTree-based OrderedContainer back into zope.container, in which case I'll gladly add support for it in ZODBBrowser. ;-)

[Marius Gedminas (mgedmin)]

This should be fixed in trunk, with a caveat: when _data is not a persistent object, you will not see accurate contents of historical versions. In fact you will probably get exceptions because _order and _data will be out of sync...