from: http://stackoverflow.com/questions/9675127/tastypie-negation-filter

tasty_pie_negation_filters.py

def apply_filters(self, request, applicable_filters):
    """
    An ORM-specific implementation of ``apply_filters``.

    The default simply applies the ``applicable_filters`` as ``**kwargs``,
    but should make it possible to do more advanced things.
    """
    positive_filters = {}
    negative_filters = {}
    for lookup in applicable_filters.keys():
        if lookup.endswith( '__not_eq' ):
            negative_filters[ lookup ] = applicable_filters[ lookup ]
        else:
            positive_filters[ lookup ] = applicable_filters[ lookup ]

    return self.get_object_list(request).filter(**positive_filters).exclude(**negative_filters)