get_roles failed when only users is given as parameter about django-permissions HOT 1 OPEN

ValueError                                Traceback (most recent call last)
<ipython-input-3-7f9c5fd36175> in <module>()
----> 1 get_roles(s)

/home/fox/prog/workspace/django-1.8/src/django-permissions/permissions/utils.pyc in get_roles(user, obj)
    218     if groups_ids_str:
    219         prrs = PrincipalRoleRelation.objects.filter(
--> 220             Q(user_id=user.id) | Q(group_id__in=groups_ids_str), content_id=None
    221         ).values("role_id")
    222     else:

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/manager.pyc in manager_method(self, *args, **kwargs)
    125         def create_method(name, method):
    126             def manager_method(self, *args, **kwargs):
--> 127                 return getattr(self.get_queryset(), name)(*args, **kwargs)
    128             manager_method.__name__ = method.__name__
    129             manager_method.__doc__ = method.__doc__

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/query.pyc in filter(self, *args, **kwargs)
    677         set.
    678         """
--> 679         return self._filter_or_exclude(False, *args, **kwargs)
    680 
    681     def exclude(self, *args, **kwargs):

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/query.pyc in _filter_or_exclude(self, negate, *args, **kwargs)
    695             clone.query.add_q(~Q(*args, **kwargs))
    696         else:
--> 697             clone.query.add_q(Q(*args, **kwargs))
    698         return clone
    699 

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/sql/query.pyc in add_q(self, q_object)
   1302         existing_inner = set(
   1303             (a for a in self.alias_map if self.alias_map[a].join_type == INNER))
-> 1304         clause, require_inner = self._add_q(where_part, self.used_aliases)
   1305         self.where.add(clause, AND)
   1306         for hp in having_parts:

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/sql/query.pyc in _add_q(self, q_object, used_aliases, branch_negated, current_negated, allow_joins)
   1324                 child_clause, needed_inner = self._add_q(
   1325                     child, used_aliases, branch_negated,
-> 1326                     current_negated, allow_joins)
   1327                 joinpromoter.add_votes(needed_inner)
   1328             else:

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/sql/query.pyc in _add_q(self, q_object, used_aliases, branch_negated, current_negated, allow_joins)
   1329                 child_clause, needed_inner = self.build_filter(
   1330                     child, can_reuse=used_aliases, branch_negated=branch_negated,
-> 1331                     current_negated=current_negated, connector=connector, allow_joins=allow_joins)
   1332                 joinpromoter.add_votes(needed_inner)
   1333             target_clause.add(child_clause, connector)

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/sql/query.pyc in build_filter(self, filter_expr, branch_negated, current_negated, can_reuse, connector, allow_joins)
   1192             # refactored when composite fields lands.
   1193             condition = field.get_lookup_constraint(self.where_class, alias, targets, sources,
-> 1194                                                     lookups, value)
   1195             lookup_type = lookups[-1]
   1196         else:

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/fields/related.pyc in get_lookup_constraint(self, constraint_class, alias, targets, sources, lookups, raw_value)
   1743             value = [val[0] for val in values]
   1744             lookup_class = targets[0].get_lookup(lookup_type)
-> 1745             root_constraint.add(lookup_class(targets[0].get_col(alias, sources[0]), value), AND)
   1746         elif lookup_type == 'in':
   1747             values = [get_normalized_value(value) for value in raw_value]

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/lookups.pyc in __init__(self, lhs, rhs)
     94     def __init__(self, lhs, rhs):
     95         self.lhs, self.rhs = lhs, rhs
---> 96         self.rhs = self.get_prep_lookup()
     97         if hasattr(self.lhs, 'get_bilateral_transforms'):
     98             bilateral_transforms = self.lhs.get_bilateral_transforms()

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/lookups.pyc in get_prep_lookup(self)
    132 
    133     def get_prep_lookup(self):
--> 134         return self.lhs.output_field.get_prep_lookup(self.lookup_name, self.rhs)
    135 
    136     def get_db_prep_lookup(self, value, connection):

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/fields/__init__.pyc in get_prep_lookup(self, lookup_type, value)
    727             return self.get_prep_value(value)
    728         elif lookup_type in ('range', 'in'):
--> 729             return [self.get_prep_value(v) for v in value]
    730         elif lookup_type == 'year':
    731             try:

/home/fox/prog/workspace/django-1.8/lib/python2.7/site-packages/django/db/models/fields/__init__.pyc in get_prep_value(self, value)
    983         if value is None:
    984             return None
--> 985         return int(value)
    986 
    987     def contribute_to_class(self, cls, name, **kwargs)