A Quick Django Tip: User Profiles

I thought I would share with all of you a little trick that I've been using for quite some time in my Django applications. Personally, I find it to be very convenient and simple.

Django allows you to specify an AUTH_PROFILE_MODULE setting if you wish to maintain information about a user beyond the basic username, password, email, etc. To access the profile for a given User instance, you must do something like:

from django.contrib.auth.models import User
user = User.objects.get(pk=1)
user.get_profile().additional_info_field

That seems all find and dandy, right? Just a simple call to get_profile() isn't that difficult. However, if there is not yet an instance of whatever you set AUTH_PROFILE_MODULE to for the user in question, you'll get an error about it when you call get_profile().

My simple-minded way around this is to do something like this:

from django.db import models
from django.contrib.auth.models import User

class UserProfile(models.Model):
    user = models.ForeignKey(User, unique=True)
    additional_info_field = models.CharField(max_length=50)

User.profile = property(lambda u: UserProfile.objects.get_or_create(user=u)[0])

The magic is in the property() and get_or_create. Using the property() feature in Python, means you can just do something like:

from django.contrib.auth.models import User
user = User.objects.get(pk=1)
user.profile.additional_info_field

(with no parentheses after profile) The get_or_create method tells Django to look for any UserProfile objects whose user attribute is the user from which you are accessing the profile property. If no matches are found, an instance of UserProfile is created for you. The lambda function returns the UserProfile instance in both cases.

This trick is very simple. It's also very effective in my experience. I'm sure there are other ways of doing the same thing, but this works for me, and it's just one line of code--no need to even specify the AUTH_PROFILE_MODULE setting! You can apply the same trick to pretty much anything if you'd like. It doesn't have to be just for user profiles. Enjoy!