validate command in 1.1 hides errors in models that used to be shown

[martin maney]

Given a trivial error in a model, running "django manage.py validate" with Django 1.0.2 diagnoses the error, a spelling error/typo, very clearly (traceback trimmed, obviously):

  File "/home/rocketry/rocketry/../rocketry/event/models.py", line 5, in <module>[[br]]
    from django.contrib.contentypes.models import ContentType[[br]]
ImportError: No module named contentypes.models

With Django 1.1, it does its damndest to make you think there's something wrong in a completely different direction, making diagnosis damned near impossible:

$ python manage.py validate
Error: One or more models did not validate:
club.shiftworked: 'event' has a relation with model event.Event, which has either not been installed or is abstract.
club.attendance: 'event' has a relation with model event.Event, which has either not been installed or is abstract.

This is a clear regression in usability, at least for those of us whose code is not always flawless. BTW, at least in this case 1.1 produces the same unhelpful message for the shell command, so I don't know how you're supposed to fix bugs in models.py unless you have an older version of Django to hand.

[Karen Tracey]

This looks to be due to r10088, which changed:

        self.nesting_level += 1
        mod = __import__(app_name, {}, {}, ['models'])
        self.nesting_level -= 1
        if not hasattr(mod, 'models'):

to:

        self.nesting_level += 1
        try:
            models = import_module('.models', app_name)
        except ImportError:
            self.nesting_level -= 1

in django/db/models/loading.py

The new code's try/except ImportError is not equivalent to the old code's testing if the returned mod has a 'models' attribute, as the new code now swallows import errors that the old code used to raise.

I have no idea how to fix it, though, since I don't know what would be equivalent to what the old code did when using the new import_module.