Debugging cryptic "Error: cannot import name <Name>" on Django

Sometimes when I run manage.py I get a cryptic message in red that says Error: cannot import name <Name> and nothing else.

Obviously, this is a simple import or syntax error and with a little looking around, I can usually fix it. Other times however it takes me quite a while to figure out what exactly I did wrong. Is there a way to 开发者_如何学Pythonget Django to spit out more info in this situation?

This is an annoying problem. Luckily, it's been fixed (recently): see this ticket and this patch.

If you want to just hack your local django install (you're running under virtualenv or buildout, right?), change to the root of your django directory (the one with README, INSTALL, etc) and run this:

curl "https://code.djangoproject.com/changeset/17197?format=diff&new=17197" | patch -p3\

So, if you run django trunk > 17197, apply the patch to your django install (it applied to django 1.2 for me), or wait until django 1.4, you'll be able to do this:

./manage.py shell --traceback

And you'll get a full traceback instead of just the Error: cannot import ...

Voila!

this happens when a circular import appears, when one model is dependent on another and in turn they try and import each other while executing code.

You might want to paste the two models that are causing you issues.

That'll help us debug.

Also it tends to happen sometimes with signals so if you have a signals file please paste too.