In [1]: from rest_framework import serializers

In [2]: class Foo(serializers.Serializer):

    items = serializers.ListSerializer(child=serializers.IntegerField())
   ...:     

In [3]: s = Foo({'items': [1, 2, 3]})

In [4]: s.data
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-4-b0eddb6f5f12> in <module>()
----> 1 s.data

.../rest_framework/serializers.pyc in data(self)
    420     @property
    421     def data(self):
--> 422         ret = super(Serializer, self).data
    423         return ReturnDict(ret, serializer=self)
    424 

.../rest_framework/serializers.pyc in data(self)
    175         if not hasattr(self, '_data'):
    176             if self.instance is not None and not getattr(self, '_errors', None):
--> 177                 self._data = self.to_representation(self.instance)
    178             elif hasattr(self, '_validated_data') and not getattr(self, '_errors', None):
    179                 self._data = self.to_representation(self.validated_data)

.../rest_framework/serializers.pyc in to_representation(self, instance)
    389                 ret[field.field_name] = None
    390             else:
--> 391                 ret[field.field_name] = field.to_representation(attribute)
    392 
    393         return ret

.../rest_framework/serializers.pyc in to_representation(self, data)
    520         iterable = data.all() if (hasattr(data, 'all')) else data
    521         return [
--> 522             self.child.to_representation(item) for item in iterable
    523         ]
    524 

TypeError: 'builtin_function_or_method' object is not iterable

fields.py
  62         try:                                                                    
  63             instance = getattr(instance, attr)                                  
  64         except ObjectDoesNotExist:                                              
  65             return None                                                         
  66         except AttributeError as exc:                                           
  67             try:                                                                
  68                 return instance[attr]                                           
  69             except (KeyError, TypeError, AttributeError):                       
  70                 raise exc