# -*- coding: utf-8 -*-
from __future__ import absolute_import, print_function, unicode_literals
from django.db.models.constants import LOOKUP_SEP
from .base import BaseFilterBackend
[docs]class DjangoFilterBackend(BaseFilterBackend):
"""
Filter backend for filtering Django querysets.
.. warning::
The filter backend can **ONLY** filter Django's ``QuerySet``.
Passing any other datatype for filtering will kill happy bunnies
under rainbow.
"""
name = 'django'
supported_lookups = {
'contains',
'day',
'endswith',
'exact',
'gt',
'gte',
'hour',
'icontains',
'iendswith',
'iexact',
'in',
'iregex',
'isnull',
'istartswith',
'lt',
'lte',
'minute',
'month',
'range',
'regex',
'second',
'startswith',
'week_day',
'year',
}
[docs] def get_model(self):
"""
Get the model from the given queryset
"""
return self.queryset.model
@property
def includes(self):
"""
Property which gets list of non-negated filters
By combining all non-negated filters we can optimize filtering by
calling ``QuerySet.filter`` once rather then calling it for each
filter specification.
"""
return filter(
lambda i: not i.is_negated,
self.regular_specs
)
@property
def excludes(self):
"""
Property which gets list of negated filters
By combining all negated filters we can optimize filtering by
calling ``QuerySet.exclude`` once rather then calling it for each
filter specification.
"""
return filter(
lambda i: i.is_negated,
self.regular_specs
)
def _prepare_spec(self, spec):
return '{}{}{}'.format(
LOOKUP_SEP.join(spec.components),
LOOKUP_SEP,
spec.lookup,
)
[docs] def filter_by_specs(self, queryset):
"""
Filter queryset by applying all filter specifications
The filtering is done by calling ``QuerySet.filter`` and
``QuerySet.exclude`` as appropriate.
"""
include = {self._prepare_spec(i): i.value for i in self.includes}
exclude = {self._prepare_spec(i): i.value for i in self.excludes}
if include:
queryset = queryset.filter(**include)
if exclude:
queryset = queryset.exclude(**exclude)
return queryset.distinct()