Lambda prevents models using this field from pickling

[jonathanpglick]

I'm trying to set up object caching for my Django project but the Any Urlfields I'm using are keeping the python serializer from pickling. It seems that this use of a lambda is causing it to throw this error:

 Can't pickle <type 'function'>: attribute lookup __builtin__.function failed

Is there a reason that you want to leave this callable?

Could the lambda be removed?

form_field = forms.ModelChoiceField(queryset=model._default_manager.all(), widget=widget)

Or if it needs to be callable, a partial function could work:

from functools import partial

def model_choice_field(model, widget):
    return forms.ModelChoiceField(queryset=model._default_manager.all(), widget=widget)
....
form_field = partial(model_choice_field, model, widget)

[vdboor]

This function should indeed be a callable, to avoid hitting the ORM too early. This function could be called from an __init__.py when someone registers a new URL type. If a partial works for you, by all means, provide a nice pull request for it!