Pyramid config loading error

I've got an issue with creating an app in Pyramid. When I try to serve through paster, I get:

  File "/home/viraptor/blah/blah/__init__.py", line 23, in main
    return config.make_wsgi_app()
  File "/home/viraptor/pyramid/lib/python2.6/site-packages开发者_运维知识库/pyramid/config.py", line 916, in make_wsgi_app
    self.commit()
  File "/home/viraptor/pyramid/lib/python2.6/site-packages/pyramid/config.py", line 491, in commit
    self._ctx.execute_actions()
  File "/home/viraptor/pyramid/lib/python2.6/site-packages/zope/configuration/config.py", line 626, in execute_actions
    callable(*args, **kw)
  File "/home/viraptor/pyramid/lib/python2.6/site-packages/pyramid/config.py", line 1291, in register
    derived_view = deriver(view)
  File "/home/viraptor/pyramid/lib/python2.6/site-packages/pyramid/config.py", line 2681, in __call__
    self.mapped_view(view))))))))
  File "/home/viraptor/pyramid/lib/python2.6/site-packages/pyramid/config.py", line 2624, in inner
    wrapped_view = wrapped(self, view)
  File "/home/viraptor/pyramid/lib/python2.6/site-packages/pyramid/config.py", line 2693, in mapped_view
    mapped_view = mapper(**self.kw)(view)
  File "/home/viraptor/pyramid/lib/python2.6/site-packages/pyramid/config.py", line 2860, in __call__
    view = self.map_nonclass(view)
  File "/home/viraptor/pyramid/lib/python2.6/site-packages/pyramid/config.py", line 2876, in map_nonclass
    ronly = requestonly(view, self.attr)
  File "/home/viraptor/pyramid/lib/python2.6/site-packages/pyramid/config.py", line 2966, in requestonly
    if len(args) - len(defaults) == 1:
zope.configuration.config.ConfigurationExecutionError: <type 'exceptions.TypeError'>: object of type 'NoneType' has no len()
  in:
  ('/home/viraptor/blah/blah/__init__.py', 22, 'main', "config.add_route('customer', '/customer/{customer_id}', view='blah.views.customer.view', view_renderer='customer_view.mak', view_permission='view', traverse='/customer/{customer_id}')")

What can be the reason for this? I haven't even changed that configuration lately, only the rest of the app.

I suspect you hit a bug fixed in newer revisions of Pyramid; your traceback indicates that either args or defaults is None, but that code branch cannot be reached unless args is not None, leaving the possibility that defaults is None instead. I found the following commit to Pyramids that adds a specific test for defaults being None:

https://github.com/Pylons/pyramid/commit/f168197609169fb01b65adeb3eb59d069000fe2c

I say you have a method without any defaults and only a request parameter (method(self, request), the work-around would be to add a keyword argument with a default (method(self, request, dummy=None).

Disclaimer: haven't yet had a chance to work with Pyramid, so my analysis is based purely on the Pyramid codebase.

config.add_route accepts only 1 positional argument, your second argument should be use keyworded with pattern.

Secondly, I don't think is possible to have the same pattern for route and the traverse. With the traverse keyword you are definining where the root should start. It's explained in the Configurator API documentation.

The error exception raised could more informative though.