Mixing system and object level permissions in django

Question

I'm using django 1.6 with REST. I'm trying to incorporate object level as well as system level permissions into my app. After reading a bit I found that django-gurdian is the best way to go (as it play nice with all the other apps).

I'm a bit confused though about how system level permissions and object level permissions are being handled together. For example,

class Item(models.Model):
    ...
    class Meta:
        permissions = (
            ("item_create", "Can create an item") , # System privilege
            ("item_update", "Can update the item"), 
            ("item_delete", "Can delete the item"),
            ("item_read"  , "Can view the item")
        )

I started writing my permissions.py when I realized that i'm not entirely certain on how to test for item_create given that i don't have an item instance yet (nor I should for a system privilege).

Appreciate any words about the difference and / or how to manage them both and how the two play together.

Answer 1

1. For Guardian permssions see the djano-guardian docu: http://django-guardian.rtfd.org/
2. For Django system permissions see: https://docs.djangoproject.com/en/dev/topics/auth/default/#default-permissions

You probably must define your own methods in which the permission checking is done. Pseudo-Code:

if is_system_permission(perm):
    user.has_perm(perm)
else:
    guardian.user_has_perm(object, perm)

Cheers