Django: How to filter Users that belong to a specific group

django, python

Solution

You'll want to use Django's convention for joining across relationships to join to the group table in your query set.

Firstly, I recommend giving your relationship a `related_name`. This makes the code more readable than what Django generates by default.

class Group(models.Model):
    myuser = models.ForeignKey(User, related_name='groups')

If you want only a single group, you can join across that relationship and compare the name field using either of these methods:

form.fields['myuser'].queryset = User.objects.filter(
    groups__name='foo')
form.fields['myuser'].queryset = User.objects.filter(
    groups__name__in=['foo'])

If you want to qualify multiple groups, use the `in` clause:

form.fields['myuser'].queryset = User.objects.filter(
    groups__name__in=['foo', 'bar'])

If you want to quickly see the generated SQL, you can do this:

qs = User.objects.filter(groups__name='foo')
print qs.query

Problem

I'm looking to narrow a query set for a form field that has a foreignkey to the User's table down to the group that a user belongs to. The groups have been previously associated by me. The model might have something like the following: ``` myuser = models.ForeignKey(User) ``` And my ModelForm is very bare bones: ``` class MyForm(ModelForm): class Meta: model = MyModel ``` So when I instantiate the form I do something like this in my views.py: ``` form = MyForm() ``` Now my question is, how can I take the myuser field, and filter it so only users of group 'foo' show up.. something like: ``` form.fields["myuser"].queryset = ??? ``` The query in SQL looks like this: ``` mysql> SELECT * from auth_user INNER JOIN auth_user_groups ON auth_user.id = auth_user_groups.user_id INNER JOIN auth_group ON auth_group.id = auth_user_groups.group_id WHERE auth_group.name = 'client'; ``` I'd like to avoid using raw SQL though. Is it possible to do so?

Original source