Django models with OneToOne relationships?

Question

Let's say I'm using the default auth.models.User plus my custom Profile and Address models which look like this:

class Profile(models.Model):
    user = models.OneToOneField(User)
    primary_phone = models.CharField(max_length=20)
    address = models.ForeignKey(Address)

class Address(models.Model):
    country = CountryField(default='CA')
    province = CAProvinceField(default='BC')
    city = models.CharField(max_length=80)
    postal_code = models.CharField(max_length=6)
    street1 = models.CharField(max_length=80)
    street2 = models.CharField(max_length=80, blank=True, null=True)
    street3 = models.CharField(max_length=80, blank=True, null=True)

Now I want to create a registration form. I could create a ModelForm based on User but that won't include fields for the Profile and Address (which are required). So what's the best way to go about building this form? Should I even use ModelForm at all?

Furthermore, how would I use the same form for editing the complex object? I could easily pass an instance of Profile back to it, which holds references to the necessary Address and Profile objects, but how do I get it to fill in the fields for me?

Answer 1

You should look into the officially recommended way to extend the User model first, as seen in the docs, which I believe comes directly from the project manager's personal blog about the subject. (The actual blog article is rather old, now)

As for your actual issue with forms, have a look at the project manager's own reusable django-profiles app and see if perusing the code solves your issue. Specifically these functions and the views in which they are utilized.

Edited to Add:

I've looked into it a bit (as I needed to do so myself). It seems something like so would be sufficient:

# apps.profiles.models

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

class UserProfile(models.Model):
    user = models.ForeignKey(User, unique=True)
    ...
    birth_date = models.DateField(blank=True, null=True)
    joined = models.DateTimeField(auto_now_add=True)
    modified = models.DateTimeField(auto_now=True)

    class Meta:
        verbose_name = 'user profile'
        verbose_name_plural = 'user profiles'
        db_table = 'user_profiles'

class Address(models.Model):
    user = models.ForeignKey(UserProfile)
    ...

# apps.profiles.forms

from django import forms
from django.forms import ModelForm
from django.forms.models import inlineformset_factory
from django.contrib.auth.models import User
from apps.profiles.models import UserProfile, Address

class UserForm(ModelForm):
    class Meta:
        model = User
        ...

class UserProfileForm(ModelForm):
    class Meta:
        model = UserProfile
        ...

AddressFormSet = inlineformset_factory(UserProfile, Address)

I was using "..." to snip content in the code above. I have not yet tested this out but from looking through examples and the documentation on forms I believe this to be correct.

Note I put the FK from the Address model to the UserProfile and not the other way around, as in your question. I believe the inline formsets need this to work correctly.

Then of course in your views and templates you will end up treating UserForm, UserProfileForm, and AddressFormSet separately but they can all be inserted into the same form.

Answer 2

I think your are looking for inline formsets with model forms. This helps you to deal with multiple forms on one page and also takes care of foreign key relations.

Update:

Maybe this question helps you too: http://stackoverflow.com/questions/569468/django-multiple-models-in-one-template-using-forms

Answer 3

What about using 3 separate ModelForm. One for Address, one for User, and one for Profile but with :

class ProfileForm(ModelForm):
  class Meta:
    model = Profile
    exclude = ('user', 'address',)

Then, process these 3 forms separately in your views. Specifically, for the ProfileForm use save with commit=False to update user and address field on the instance :

# ...
profile_form = ProfileForm(request.POST)
if profile_form.is_valid():
  profile = profile_form.save(commit=False)
  # `user` and `address` have been created previously
  # by saving the other forms
  profile.user = user
  profile.address = address

Don't hesitate to use transactions here to be sure rows get inserted only when the 3 forms are valid.