Restrict the listed assignments for the current user.

def get_queryset(self, request):
        ''' Restrict the listed assignments for the current user.'''
        qs = super(AssignmentAdmin, self).get_queryset(request)
        if not request.user.is_superuser:
            qs = qs.filter(course__active=True).filter(Q(course__tutors__pk=request.user.pk) | Q(course__owner=request.user)).distinct()
        return qs.order_by('title')