Question

How can you have model declarations at two different directories in Django?

I have the model at the directory Code which contains "init.py", "models.py" and "admin.py". It is working properly alone.

I want to have the directory History which has the model of the revisions of the given questions. I have the similar files in the directory.

I need to tell Django to use the model at the directory "History" somehow, since I have a ManyToMany relation in the table Questions to the other directory.

I get the following import error

ImportError at /

cannot import name history

Request Method:     GET
Request URL:    http://127.0.0.1:8000/
Exception Type:     ImportError
Exception Value:    

cannot import name history

Exception Location:     /home/noa/build/CML/../CML/codes/models.py in <module>, line 2
Python Executable:  /usr/bin/python
Python Version:     2.6.2
Python Path:    [ /home/noa/build/CML ,  /usr/lib/python2.6 ,  /usr/lib/python2.6/plat-linux2 ,  /usr/lib/python2.6/lib-tk ,  /usr/lib/python2.6/lib-old ,  /usr/lib/python2.6/lib-dynload ,  /usr/lib/python2.6/dist-packages ,  /usr/lib/python2.6/dist-packages/PIL ,  /usr/lib/python2.6/dist-packages/gst-0.10 ,  /var/lib/python-support/python2.6 ,  /usr/lib/python2.6/dist-packages/gtk-2.0 ,  /var/lib/python-support/python2.6/gtk-2.0 ,  /var/lib/python-support/python2.6/pyinotify ,  /usr/lib/python2.6/dist-packages/wx-2.8-gtk2-unicode ,  /usr/local/lib/python2.6/dist-packages ]
Server time:    Fri, 11 Dec 2009 15:46:30 -0600

Answer 1

Since it sounds like both of your directories are Django apps, and assuming you ve put both of them in your INSTALLED_APPS list in settings.py you can refer to them using a string without having to import:

# in code/models.py

class Questions(models.Model):
    histories = models.ManyToManyField( history.MyHistoryModel )

Note that the path is case sensitive... so if you app is truly called History you will need to reference it using History.MyHistoryModel .

Answer 2

Generally people just have one "models" directory, or even sometimes just one models file. If you get to the point that you feel you need 2 full directories for your models, it s probably better to start thinking about breaking your one app, into a couple of small apps instead generally. That being said, there s a number of things that could be potentially wrong just with your setup that we can t see.

Anytime I have an import error though, I drop to a python shell and try to import the item. If it fails, then something is either wrong with the module (you d be surprised how often I forget __init__.py), or it s not properly in your python path.

Answer 3

If the directory is called History, you should change import history to import History, as python imports are case-sensitive (on my Linux box, at least).

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