Question

I have recently started experimenting with Django for some web applications in my spare time. While designing the data model for one, I came across the dilemma of using inheritance to define a user of the website or using a technique known as monkey patching with the User class already supplied by the framework.

I tried to add a field by means of (after having defined all my models etc. without errors, according to python manage.py validate):

User.add_to_class('location', models.CharField(max_length=250,blank=True))

and executed the syncdb command. However, I keep getting this error

OperationalError: no such column:
auth_user.location

whether I am in the admin view of the site or the manage.py shell. There must be an extra step I’m missing, but there seems to be limited documentation on the whole monkey patching technique. So I’m asking you for assistance before I resort to inheritance. Any code, tips, or pointers to additional documentation are of course welcome.

Thanks in advance.

PS. I’m aware this technique is ugly, and probably ill-advised. 😉

Answer 1

When you add a field to any model, even if you do it the ‘official’ way, you need to migrate the database – Django doesn’t do it for you. Drop the table and run ./manage.py syncdb again.

You might want to investigate one of the migrations frameworks, such as south, which will manage this sort of thing for you.