Django Rest Framework Filters

django-rest-framework-filters is an extension to Django REST framework and Django filter that makes it easy to filter across relationships. Historically, this extension also provided a number of additional features and fixes, however the number of features has shrunk as they are merged back into django-filter.

Using django-rest-framework-filters, we can easily do stuff like:

/api/article?author__first_name__icontains=john
/api/article?is_published!=true

Table of Contents

• Features
• Requirements
• Installation
• Usage
  • Filtering across relationships
  • Supporting Filter.method
  • Automatic Filter Negation/Exclusion
  • Allowing any lookup type on a field
  • Can I mix and match django-filter and django-rest-framework-filters?
  • Caveats & Limitations
• Migrating to 1.0
  • RelatedFilter.queryset now required
  • get_filters() renamed to expand_filters()
• Publishing
• License

Features

• Easy filtering across relationships
• Support for method filtering across relationships
• Automatic filter negation with a simple param!=value syntax
• Backend caching to increase performance

Requirements

• Python: 2.7 or 3.3+
• Django: 1.8, 1.9, 1.10, 1.11
• DRF: 3.5, 3.6

Installation

$ pip install djangorestframework-filters

Usage

Upgrading from django-filter to django-rest-framework-filters is straightforward:

• Import from rest_framework_filters instead of from django_filters
• Use the rest_framework_filters backend instead of the one provided by django_filter.

# django-filter
from django_filters.rest_framework import FilterSet, filters

class ProductFilter(FilterSet):
    manufacturer = filters.ModelChoiceFilter(queryset=Manufacturer.objects.all())
    ...


# django-rest-framework-filters
import rest_framework_filters as filters

class ProductFilter(filters.FilterSet):
    manufacturer = filters.ModelChoiceFilter(queryset=Manufacturer.objects.all())
    ...

To use the django-rest-framework-filters backend, add the following to your settings:

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

Once configured, you can continue to use all of the filters found in django-filter.

Filtering across relationships

You can easily traverse multiple relationships when filtering by using RelatedFilter:

from rest_framework import viewsets
import rest_framework_filters as filters


class ManagerFilter(filters.FilterSet):
    class Meta:
        model = Manager
        fields = {'name': ['exact', 'in', 'startswith']}


class DepartmentFilter(filters.FilterSet):
    manager = filters.RelatedFilter(ManagerFilter, name='manager', queryset=Manager.objects.all())

    class Meta:
        model = Department
        fields = {'name': ['exact', 'in', 'startswith']}


class CompanyFilter(filters.FilterSet):
    department = filters.RelatedFilter(DepartmentFilter, name='department', queryset=Department.objects.all())

    class Meta:
        model = Company
        fields = {'name': ['exact', 'in', 'startswith']}


# company viewset
class CompanyView(viewsets.ModelViewSet):
    filter_class = CompanyFilter
    ...

Example filter calls:

/api/companies?department__name=Accounting
/api/companies?department__manager__name__startswith=Bob

queryset callables

Since RelatedFilter is a subclass of ModelChoiceFilter, the queryset argument supports callable behavior. In the following example, the set of departments is restricted to those in the user's company.

def departments(request):
    company = request.user.company
    return company.department_set.all()

class EmployeeFilter(filters.FilterSet):
    department = filters.RelatedFilter(filterset=DepartmentFilter, queryset=departments)
    ...

Recursive relationships

Recursive relations are also supported. It may be necessary to specify the full module path.

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

    class Meta:
        model = Person

Supporting Filter.method

django_filters.MethodFilter has been deprecated and reimplemented as the method argument to all filter classes. It incorporates some of the implementation details of the old rest_framework_filters.MethodFilter, but requires less boilerplate and is simpler to write.

• It is no longer necessary to perform empty/null value checking.
• You may use any filter class (CharFilter, BooleanFilter, etc...) which will validate input values for you.
• The argument signature has changed from (name, qs, value) to (qs, name, value).

class PostFilter(filters.FilterSet):
    # Note the use of BooleanFilter, the original model field's name, and the method argument.
    is_published = filters.BooleanFilter(name='date_published', method='filter_is_published')

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

    def filter_is_published(self, qs, name, value):
        """
        `is_published` is based on the `date_published` model field.
        If the publishing date is null, then the post is not published.
        """
        # incoming value is normalized as a boolean by BooleanFilter
        isnull = not value
        lookup_expr = LOOKUP_SEP.join([name, 'isnull'])

        return qs.filter(**{lookup_expr: isnull})

class AuthorFilter(filters.FilterSet):
    posts = filters.RelatedFilter('PostFilter', queryset=Post.objects.all())

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

The above would enable the following filter 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.

Automatic Filter Negation/Exclusion

FilterSets support automatic exclusion using a simple param!=value 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

Note that most filters only accept a single query parameter. In the above, title__contains and title__contains! are interpreted as two separate query parameters. The following would probably be invalid, although it depends on the specifics of the individual filter class:

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

Allowing any lookup type on a field

If you need to enable several lookups for a field, django-filter provides the dict-syntax for Meta.fields.

class ProductFilter(filters.FilterSet):
    class Meta:
        model = Product
        fields = {
            'price': ['exact', 'lt', 'gt', ...],
        }

django-rest-framework-filters also allows you to enable all possible lookups for any field. This can be achieved through the use of AllLookupsFilter or using the '__all__' value in the Meta.fields dict-style syntax. Generated filters (Meta.fields, AllLookupsFilter) will never override your declared filters.

Note that using all lookups comes with the same admonitions as enabling '__all__' fields in django forms (docs). Exposing all lookups may allow users to construct queries that inadvertently leak data. Use this feature responsibly.

class ProductFilter(filters.FilterSet):
    # Not overridden by `__all__`
    price__gt = filters.NumberFilter(name='price', lookup_expr='gt', label='Minimum price')

    class Meta:
        model = Product
        fields = {
            'price': '__all__',
        }

# or

class ProductFilter(filters.FilterSet):
    price = filters.AllLookupsFilter()

    # Not overridden by `AllLookupsFilter`
    price__gt = filters.NumberFilter(name='price', lookup_expr='gt', label='Minimum price')

    class Meta:
        model = Product

You cannot combine AllLookupsFilter with RelatedFilter as the filter names would clash.

class ProductFilter(filters.FilterSet):
    manufacturer = filters.RelatedFilter('ManufacturerFilter', queryset=Manufacturer.objects.all())
    manufacturer = filters.AllLookupsFilter()

To work around this, you have the following options:

class ProductFilter(filters.FilterSet):
    manufacturer = filters.RelatedFilter('ManufacturerFilter', queryset=Manufacturer.objects.all())

    class Meta:
        model = Product
        fields = {
            'manufacturer': '__all__',
        }

# or

class ProductFilter(filters.FilterSet):
    manufacturer = filters.RelatedFilter('ManufacturerFilter', queryset=Manufacturer.objects.all(), lookups='__all__')  # `lookups` also accepts a list

    class Meta:
        model = Product

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

Yes you can. django-rest-framework-filters is simply an extension of django-filter. Note that RelatedFilter and other django-rest-framework-filters features are designed to work with rest_framework_filters.FilterSet and will not function on a django_filters.FilterSet. However, the target RelatedFilter.filterset may point to a FilterSet from either package, and both FilterSet implementations are compatible with the other's DRF backend.

# valid
class VanillaFilter(django_filters.FilterSet):
    ...

class DRFFilter(rest_framework_filters.FilterSet):
    vanilla = rest_framework_filters.RelatedFilter(filterset=VanillaFilter, queryset=...)


# invalid
class DRFFilter(rest_framework_filters.FilterSet):
    ...

class VanillaFilter(django_filters.FilterSet):
    drf = rest_framework_filters.RelatedFilter(filterset=DRFFilter, queryset=...)

Caveats & Limitations

MultiWidget is incompatible

djangorestframework-filters is not compatible with form widgets that parse query names that differ from the filter's attribute name. Although this only practically applies to MultiWidget, it is a general limitation that affects custom widgets that also have this behavior. Affected filters include RangeFilter, DateTimeFromToRangeFilter, DateFromToRangeFilter, TimeRangeFilter, and NumericRangeFilter.

To demonstrate the incompatiblity, take the following filterset:

class PostFilter(FilterSet):
    publish_date = filters.DateFromToRangeFilter()

The above filter allows users to perform a range query on the publication date. The filter class internally uses MultiWidget to separately parse the upper and lower bound values. The incompatibility lies in that MultiWidget appends an index to its inner widget names. Instead of parsing publish_date, it expects publish_date_0 and publish_date_1. It is possible to fix this by including the attribute name in the querystring, although this is not recommended.

?publish_date_0=2016-01-01&publish_date_1=2016-02-01&publish_date=

MultiWidget is also discouraged since:

• core-api field introspection fails for similar reasons
• _0 and _1 are less API-friendly than _min and _max

The recommended solutions are to either:

• Create separate filters for each of the sub-widgets (such as publish_date_min and publish_date_max).
• Use a CSV-based filter such as those derived from BaseCSVFilter/BaseInFilter/BaseRangeFilter. eg,

?publish_date__range=2016-01-01,2016-02-01

Migrating to 1.0

RelatedFilter.queryset now required

The related filterset's model is no longer used to provide the default value for RelatedFilter.queryset. This change reduces the chance of unintentionally exposing data in the rendered filter forms. You must now explicitly provide the queryset argument, or override the get_queryset() method (see queryset callables).

get_filters() renamed to expand_filters()

django-filter has add a get_filters() classmethod to it's API, so this method has been renamed.

Publishing

$ pip install -U twine setuptools wheel
$ rm -rf dist/ build/
$ python setup.py sdist bdist_wheel
$ twine upload dist/*

License

Copyright (c) 2013-2015 Philip Neustrom <philipn@gmail.com>, 2016-2017 Ryan P Kilby <rpkilby@ncsu.edu>

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.