'Returns field\'s value prepared for database lookup.'

def get_db_prep_lookup(self, lookup_type, value, connection=None, prepared=None):

    if (value.tzinfo is None):
        value = default_tz.localize(value)
    else:
        value = value.astimezone(default_tz)
    return super(LocalizedDateTimeField, self).get_db_prep_lookup(lookup_type, value, connection=connection, prepared=prepared)
