signalkraft/django-rest-framework-filters

Better filtering for Django REST Framework

django-rest-framework-filters is an extension to Django REST framework that makes working with filtering much easier. In addition to fixing some underlying warts and limitations of django-filter, we allow arbitrary chaining of both relations and lookup filters.

E.g. using django-rest-framework-filters instead of just django-filter, we can do stuff like:

/api/page/?author__username__icontains=john
/api/page/?author__username__endswith=smith

Without having to create a zillion filter fields by hand.

Installation

$ pip install djangorestframework-filters

Requirements

• Python 2.7+
• Django 1.8+
• Django REST framework 3.0+

Usage

Here's how you were probably doing filtering before:

import django_filters
from myapp.models import Product

class ProductFilter(django_filters.FilterSet):
    manufacturer = django_filters.CharFilter(name="manufacturer__name")

    class Meta:
        model = Product
        fields = ['category', 'in_stock', 'manufacturer']

To use django-rest-framework-filters, simply import rest_framework_filters instead of django_filters:

import rest_framework_filters as filters
from myapp.models import Product

class ProductFilter(filters.FilterSet):
    manufacturer = filters.CharFilter(name="manufacturer__name")

    class Meta:
        model = Product
        fields = ['category', 'in_stock', 'manufacturer']

All filters found in django-filter are available for usage. In this case, there's nothing new that's gained. But read onward!

Chaining filtering through relations

To enable chained filtering through relations:

from rest_framework import viewsets
import rest_framework_filters as filters

class UserFilter(filters.FilterSet):
    username = filters.CharFilter(name='username')
    ...

class PageFilter(filters.FilterSet):
    title = filters.CharFilter(name='title')
    author = filters.RelatedFilter(UserFilter, name='author')
    ...

# Then just use the PageFilter as you would any other FilterSet:

class PageView(viewsets.ModelViewSet):
    ...
    filter_class = PageFilter

then we can automatically chain our filters through the author relation, as so:

/api/page/?author__username=philipn

Recursive relations are also supported. You will need to specify the full module path in the RelatedFilter definition in some cases, e.g.:

class PersonFilter(filters.FilterSet):
    name = filters.AllLookupsFilter(name='name')
    best_friend = filters.RelatedFilter('people.views.PersonFilter', name='best_friend')

    class Meta:
        model = Person

Allowing any lookup type on a field

We can use the AllLookupsFilter to allow all possible lookup types on a particular field. While we could otherwise specify these by hand, e.g.:

class ProductFilter(filters.FilterSet):
    min_price = filters.NumberFilter(name="price", lookup_type='gte')
    ...

to allow the price__gte lookup. But this gets cumbersome, and we sometimes want to allow any possible lookups on particular fields. We do this by using AllLookupsFilter:

from rest_framework import viewsets
import rest_framework_filters as filters

class PageFilter(filters.FilterSet):
    title = filters.AllLookupsFilter(name='title')
    ...

then we can use any possible lookup on the title field, e.g.:

/api/page/?title__icontains=park

or :

/api/page/?title__startswith=The

and also filter on the default lookup (exact), as usual:

/api/page/?title=The%20Park

Additionally, you may use ALL_LOOKUPS with dictionary style declarations.

import rest_framework_filters as filters

class PageFilter(filters.FilterSet):
    ...

    class Meta:
        fields = {
            'title': filters.ALL_LOOKUPS,
        }

Combining RelatedFilter and AllLookupsFilter

We can combine RelatedFilter and AllLookupsFilter:

from rest_framework import viewsets
import rest_framework_filters as filters

class PageFilter(filters.FilterSet):
    title = filters.CharFilter(name='title')
    author = filters.RelatedFilter(UserFilter, name='author')

class UserFilter(filters.FilterSet):
    username = AllLookupsFilter(name='username')
    ...

then we can filter like so:

/api/page/?author__username__icontains=john

Automatic Filter Negation/Exclusion

FilterSets also support automatic exclusion using a simple k!=v syntax. This syntax internally sets the exclude property on the filter.

/api/page/?title!=The%20Park

This syntax supports regular filtering combined with exclusion filtering. For example, the following would search for all articles containing "Hello" in the title, while excluding those containing "World".

/api/articles/?title__contains=Hello&title__contains!=World

MethodFilter Reimplementation

MethodFilter has been reimplemented to work across relationships. This is not a forwards-compatible change and requires adding a minimal amount of boilerplate to the filter method.

When filtering across relationships, the queryset and lookup value will be different. For example:

class PostFilter(filters.FilterSet):
    author = filters.RelatedFilter('AuthorFilter')
    is_published = filters.MethodFilter()

    class Meta:
        model = Post
        fields = ['title', 'content']

    def filter_is_published(self, name, qs, value):
        # convert value to boolean
        null = value.lower() != 'true'

        # The lookup name will end with `is_published`, but could be
        # preceded by a related lookup path.
        if LOOKUP_SEP in name:
            rel, _ = name.rsplit(LOOKUP_SEP, 1)
            name = LOOKUP_SEP.join([rel, 'date_published__isnull'])
        else:
            name = 'date_published__isnull'

        return qs.filter(**{name: null})

class AuthorFilter(filters.FilterSet):
    posts = filters.RelatedFilter('PostFilter')

    class Meta:
        model = Author
        fields = ['name']

And given these API calls:

/api/posts/?is_published=true

/api/authors/?posts__is_published=true

In the first API call, the filter method receives a queryset of posts. In the second, it receives a queryset of users. The filter method in the example modifies the lookup name to work across the relationship, allowing you to find published posts, or authors who have published posts.

DjangoFilterBackend

We implement our own subclass of DjangoFilterBackend, which you should probably use instead of the default DjangoFilterBackend. Our DjangoFilterBackend caches repeated filter set generation — a particularly important optimization when using RelatedFilter and AllLookupsFilter.

To use our FilterBackend, in your settings.py`, simply use:

REST_FRAMEWORK = {
    ...
    'DEFAULT_FILTER_BACKENDS': (
        'rest_framework_filters.backends.DjangoFilterBackend', ...
    ),

instead of the default rest_framework.filters.DjangoFilterBackend.

What warts are fixed?

Even if you're not using RelatedFilter or AllLookupsFilter, you will probably want to use django-rest-framework-filters. For instance, if you simply use django-filter it is very difficult to filter on a DateTimeFilter in the date format emitted by the default serializer (ISO 8601), which makes working with your API difficult.

Can I mix and match django-filter and django-rest-framework-filters?

Yes you can. django-rest-framework-filters extends django-filter, and you can mix and match them as you please. For a given class, you should use only one of django-filter or django-rest-framework-filters, but you can use RelatedFilter to link to a filter relation defined elsewhere that uses vanilla django-filter.

Caveats

djangorestframework-filters is not compatible with the filterset's order_by meta option. Use rest_framework.filters.OrderingFilter instead if you need to support ordering.

License

Copyright (c) 2013-2015 Philip Neustrom <[email protected]>, 2016 Ryan P Kilby <[email protected]>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.