Assign object permissions

Assigning object permissions should be very simple once permissions are created for models.

Prepare permissions

Let’s assume we have following model:

class Task(models.Model):
    summary = models.CharField(max_length=32)
    content = models.TextField()
    reported_by = models.ForeignKey(User)
    created_at = models.DateTimeField(auto_now_add=True)

... and we want to be able to set custom permission view_task. We let know Django to do so by adding permissions tuple to Meta class and our final model could look like:

class Task(models.Model):
    summary = models.CharField(max_length=32)
    content = models.TextField()
    reported_by = models.ForeignKey(User)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        permissions = (
            ('view_task', 'View task'),
        )

After we call syncdb management command our view_task permission would be added to default set of permissions.

Note

By default, Django adds 3 permissions for each registered model:

• add_modelname
• change_modelname
• delete_modelname

(where modelname is a simplified name of our model’s class). See http://docs.djangoproject.com/en/1.2/topics/auth/#default-permissions for more detail.

There is nothing new here since creation of permissions is handled by django. Now we can move to assign-obj-perms.

Assign object permissions

We can assign permissions for any user/group and object pairs using same, convenient function: guardian.shortcuts.assign().

For user

Continuing our example we now can allow Joe user to view some task:

>>> boss = User.objects.create(username='Big Boss')
>>> joe = User.objects.create(username='joe')
>>> task = Task.objects.create(summary='Some job', content='', reported_by=boss)
>>> joe.has_perm('view_task', task)
False

Well, not so fast Joe, let us create an object permission finally:

>>> from guardian.shortcuts import assign
>>> assign('view_task', joe, task)
>>> joe.has_perm('view_task', task)
True

For group

This case doesn’t really differ from user permissions assignment. The only difference is we have to pass Group instance rather than User.

>>> group = Group.objects.create(name='employees')
>>> assign('change_task', group, task)
>>> joe.has_perm('change_task', task)
False
>>> # Well, joe is not yet within an *employees* group
>>> joe.groups.add(group)
>>> joe.has_perm('change_task', task)
True