When should I use user.get_profile in django?

Question

I saw another answer here and other places on the web that recommend using user.get_profile when extending the built-in django user. I didn't do that in the below example. The functionality seems to be working fine, but is there a downside for not using user.get_profile()?

model

class UserProfile(models.Model):
    user = models.ForeignKey(User, primary_key=True)
    quote = models.CharField('Favorite quote', max_length =  200, null=True, blank=True)
    website = models.URLField('Personal website/blog', null=True, blank=True)

class UserProfileForm(ModelForm):
    class Meta:
        model = UserProfile
        fields = ('quote', 'website')

view

@login_required 
def user_profile(request):
    user = User.objects.get(pk=request.user.id)
    if request.method == 'POST':
        upform = UserProfileForm(request.POST)
        if upform.is_valid():
            up = upform.save(commit=False)
            up.user = request.user
            up.save()
            return HttpResponseRedirect('/accounts/profile')
    else:
        upform = UserProfileForm()
    return render_to_response('reserve/templates/edit_profile.html', locals(), context_instance=RequestContext(request))

Answer 1

The code works as you've written it, but because you don't pass an instance to your model it's a bit unusual, so it might take another Django developer a bit longer to work out what's going on.

The view you link to instantiates the model form with an instance, so that the existing profile values are displayed in the form. In your case, you'll get empty fields.

upform = UserProfileForm(instance=user.get_profile())

Because you don't provide an instance, saving would try to create a new user_profile, which we wouldn't want. That won't happen in your case, because you've made user the primary key, but that's a little unusual as well.

The main advantage of writing user.get_profile() is that you don't need to know which model is used for the user profile. If you are happy to hardcode UserProfile model in your code, you could put instance=UserProfile.objects.get(user=user) instead.