django-rest-framework-datatables documentation

Seamless integration between Django REST framework and Datatables.

Django Rest Framework + Datatables = Awesome :)

Introduction

django-rest-framework-datatables provides seamless integration between Django REST framework and Datatables.

Just call your API with ?format=datatables, and you will get a JSON structure that is fully compatible with what Datatables expects.

A “normal” call to your existing API will look like this:

$ curl http://127.0.0.1:8000/api/albums/ | python -m "json.tool"

{
    "count": 2,
    "next": null,
    "previous": null,
    "results": [
        {
            "rank": 1,
            "name": "Sgt. Pepper's Lonely Hearts Club Band",
            "year": 1967,
            "artist_name": "The Beatles",
            "genres": "Psychedelic Rock, Rock & Roll"
        },
        {
            "rank": 2,
            "name": "Pet Sounds",
            "year": 1966,
            "artist_name": "The Beach Boys",
            "genres": "Pop Rock, Psychedelic Rock"
        }
    ]
}

The same call with datatables format will look a bit different:

$ curl http://127.0.0.1:8000/api/albums/?format=datatables | python -m "json.tool"

{
    "recordsFiltered": 2,
    "recordsTotal": 2,
    "draw": 1,
    "data": [
        {
            "rank": 1,
            "name": "Sgt. Pepper's Lonely Hearts Club Band",
            "year": 1967,
            "artist_name": "The Beatles",
            "genres": "Psychedelic Rock, Rock & Roll"
        },
        {
            "rank": 2,
            "name": "Pet Sounds",
            "year": 1966,
            "artist_name": "The Beach Boys",
            "genres": "Pop Rock, Psychedelic Rock"
        }
    ]
}

As you can see, django-rest-framework-datatables automatically adapt the JSON structure to what Datatables expects. And you don’t have to create a different API, your API will still work as usual unless you specify the datatables format on your request.

But django-rest-framework-datatables can do much more ! As you will learn in the tutorial, it speaks the Datatables language and can handle searching, filtering, ordering, pagination, etc. Read the quickstart guide for instructions on how to install and configure django-rest-framework-datatables.

Quickstart

Installation

Just use pip:

$ pip install djangorestframework-datatables

Configuration

To enable Datatables support in your project, add 'rest_framework_datatables' to your INSTALLED_APPS, and modify your REST_FRAMEWORK settings like this:

REST_FRAMEWORK = {
    'DEFAULT_RENDERER_CLASSES': (
        'rest_framework.renderers.JSONRenderer',
        'rest_framework.renderers.BrowsableAPIRenderer',
        'rest_framework_datatables.renderers.DatatablesRenderer',
    ),
    'DEFAULT_FILTER_BACKENDS': (
        'rest_framework_datatables.filters.DatatablesFilterBackend',
    ),
    'DEFAULT_PAGINATION_CLASS': 'rest_framework_datatables.pagination.DatatablesPageNumberPagination',
    'PAGE_SIZE': 50,
}

What have we done so far ?

• we added the rest_framework_datatables.renderers.DatatablesRenderer to existings renderers
• we added the rest_framework_datatables.filters.DatatablesFilterBackend to the filter backends
• we replaced the pagination class by rest_framework_datatables.pagination.DatatablesPageNumberPagination

Note

If you are using rest_framework.pagination.LimitOffsetPagination as pagination class, relax and don’t panic ! django-rest-framework-datatables can handle that, just replace it with rest_framework_datatables.pagination.DatatablesLimitOffsetPagination.

And that’s it !

Your API is now fully compatible with Datatables and will provide searching, filtering, ordering and pagination without any modification of your API code, to continue, follow the tutorial.

Tutorial

Note

The purpose of this section is not to replace the excellent Django REST Framework documentation nor the Datatables manual, it is just to give you hints and gotchas for using your datatables compatible API.

Backend code

So we have the following backend code, nothing very complicated if you are familiar with Django and Django REST Framework:

albums/models.py:

from django.db import models


class Genre(models.Model):
    name = models.CharField('Name', max_length=80)

    class Meta:
        ordering = ['name']

    def __str__(self):
        return self.name


class Artist(models.Model):
    name = models.CharField('Name', max_length=80)

    class Meta:
        ordering = ['name']

    def __str__(self):
        return self.name


class Album(models.Model):
    name = models.CharField('Name', max_length=80)
    rank = models.PositiveIntegerField('Rank')
    year = models.PositiveIntegerField('Year')
    artist = models.ForeignKey(
        Artist,
        models.CASCADE,
        verbose_name='Artist',
        related_name='albums'
    )
    genres = models.ManyToManyField(
        Genre,
        verbose_name='Genres',
        related_name='albums'
    )

    class Meta:
        ordering = ['name']

    def __str__(self):
        return self.name

albums/serializers.py:

from rest_framework import serializers
from .models import Album

class ArtistSerializer(serializers.ModelSerializer):
    id = serializers.IntegerField(read_only=True)

    class Meta:
        model = Artist
        fields = (
            'id', 'name',
        )


class AlbumSerializer(serializers.ModelSerializer):
    artist = ArtistSerializer()
    genres = serializers.SerializerMethodField()

    def get_genres(self, album):
        return ', '.join([str(genre) for genre in album.genres.all()])

    class Meta:
        model = Album
        fields = (
            'rank', 'name', 'year', 'artist_name', 'genres',
        )

albums/views.py:

from django.shortcuts import render
from rest_framework import viewsets
from .models import Album
from .serializers import AlbumSerializer


def index(request):
    return render(request, 'albums/albums.html')


class AlbumViewSet(viewsets.ModelViewSet):
    queryset = Album.objects.all().order_by('rank')
    serializer_class = AlbumSerializer

urls.py:

from django.conf.urls import url, include
from rest_framework import routers
from albums import views


router = routers.DefaultRouter()
router.register(r'albums', views.AlbumViewSet)


urlpatterns = [
    url('^api/', include(router.urls)),
    url('', views.index, name='albums')
]

A minimal datatable

In this example, we will build a simple table that will list music albums, we will display 3 columns, the album rank, name and release year. For the sake of simplicity we will also use HTML5 data attributes (which are supported by Datatables).

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Rolling Stone Top 500 albums of all time</title>
  <meta name="description" content="Rolling Stone magazine's 2012 list of 500 greatest albums of all time with genres.">
  <link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0/css/bootstrap.css">
  <link rel="stylesheet" href="//cdn.datatables.net/1.10.16/css/dataTables.bootstrap4.min.css">
</head>

<body>
  <div class="container">
    <div class="row">
      <div class="col-sm-12">
        <table id="albums" class="table table-striped table-bordered" style="width:100%" data-server-side="true" data-ajax="/api/albums/?format=datatables">
          <thead>
            <tr>
              <th data-data="rank">Rank</th>
              <th data-data="name">Album name</th>
              <th data-data="year">Year</th>
            </tr>
          </thead>
        </table>
      </div>
    </div>
  </div>
  <script src="//code.jquery.com/jquery-1.12.4.js"></script>
  <script src="//cdn.datatables.net/1.10.16/js/jquery.dataTables.min.js"></script>
  <script src="//cdn.datatables.net/1.10.16/js/dataTables.bootstrap4.min.js"></script>
  <script>
      $(document).ready(function() {
          $('#albums').DataTable();
      });
  </script>
</body>
</html>

And that’s it ! At this point, you should have a fully functional Datatable with search, ordering and pagination !

What we just did:

• included all the necessary CSS and JS files
• set the table data-server-side attribute to true, to tell Datatables to use the server-side processing mode
• set the table data-ajax to our API URL with ?format=datatables as query parameter
• set a data-data attribute for the two columns to tell Datatables what properties must be extracted from the response
• and finally initialized the Datatable via a javascript one-liner.

Perhaps you noticed that we didn’t use all fields from our serializer in the above example, that’s not a problem, django-rest-framework-datatables will automatically filter the fields that are not necessary when processing the request from Datatables.

If you want to force serialization of fields that are not requested by Datatables you can use the datatables_always_serialize Meta option in your serializer, here’s an example:

class AlbumSerializer(serializers.ModelSerializer):
    id = serializers.IntegerField(read_only=True)
    class Meta:
        model = Album
        fields = (
            'id', 'rank', 'name', 'year',
        )
        datatables_always_serialize = ('id', 'rank',)

In the above example, the fields ‘id’ and ‘rank’ will always be serialized in the response regardless of fields requested in the Datatables request.

Hint

Alternatively, if you wish to choose which fields to preserve at runtime rather than hardcoding them into your serializer models, use the ?keep= param along with the fields you wish to maintain (comma separated). For example, if you wished to preserve id and rank as before, you would simply use the following API call:

data-ajax="/api/albums/?format=datatables&keep=id,rank"

In order to provide additional context of the data from the view, you can use the datatables_extra_json Meta option.

class AlbumViewSet(viewsets.ModelViewSet):
    queryset = Album.objects.all().order_by('rank')
    serializer_class = AlbumSerializer

    def get_options(self):
        return "options", {
            "artist": [{'label': obj.name, 'value': obj.pk} for obj in Artist.objects.all()],
            "genre": [{'label': obj.name, 'value': obj.pk} for obj in Genre.objects.all()]
        }

    class Meta:
        datatables_extra_json = ('get_options', )

In the above example, the ‘get_options’ method will be called to populate the rendered JSON with the key and value from the method’s return tuple.

Important

To sum up, the most important things to remember here are:

• don’t forget to add ?format=datatables to your API URL
• you must add a data-data attribute or specify the column data property via JS for each columns, the name must match one of the fields of your DRF serializers.

A more complex and detailed example

In this example we want to display more informations about the album:

• the album artist name (Album.artist is a foreignkey to Artist model)
• the genres (Album.genres is a many to many relation with Genre model)

The HTML/JS code will look like this:

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Rolling Stone Top 500 albums of all time</title>
  <meta name="description" content="Rolling Stone magazine's 2012 list of 500 greatest albums of all time with genres.">
  <link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0/css/bootstrap.css">
  <link rel="stylesheet" href="//cdn.datatables.net/1.10.16/css/dataTables.bootstrap4.min.css">
</head>

<body>
  <div class="container">
    <div class="row">
      <div class="col-sm-12">
        <table id="albums" class="table table-striped table-bordered" style="width:100%" data-server-side="true" data-ajax="/api/albums/?format=datatables">
          <thead>
            <tr>
              <th data-data="rank">Rank</th>
              <th data-data="artist.name" data-name="artist.name">Artist</th>
              <th data-data="name">Album name</th>
              <th data-data="year">Year</th>
              <th data-data="genres" data-name="genres.name">Year</th>
            </tr>
          </thead>
        </table>
      </div>
    </div>
  </div>
  <script src="//code.jquery.com/jquery-1.12.4.js"></script>
  <script src="//cdn.datatables.net/1.10.16/js/jquery.dataTables.min.js"></script>
  <script src="//cdn.datatables.net/1.10.16/js/dataTables.bootstrap4.min.js"></script>
  <script>
      $(document).ready(function() {
          $('#albums').DataTable();
      });
  </script>
</body>
</html>

Notice that artist and genres columns have an extra data attribute: data-name, this attribute is necessary to tell to the django-rest-framework-datatables builtin filter backend what field part to use to filter and reorder the queryset. The builtin filter will add __icontains to the string to perform the filtering/ordering.

We could also have written that in a more conventional form (without data attributes), for example:

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Rolling Stone Top 500 albums of all time</title>
  <meta name="description" content="Rolling Stone magazine's 2012 list of 500 greatest albums of all time with genres.">
  <link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0/css/bootstrap.css">
  <link rel="stylesheet" href="//cdn.datatables.net/1.10.16/css/dataTables.bootstrap4.min.css">
</head>

<body>
  <div class="container">
    <div class="row">
      <div class="col-sm-12">
        <table id="albums" class="table table-striped table-bordered" style="width:100%">
          <thead>
            <tr>
              <th>Rank</th>
              <th>Artist</th>
              <th>Album name</th>
              <th>Year</th>
              <th>Year</th>
            </tr>
          </thead>
        </table>
      </div>
    </div>
  </div>
  <script src="//code.jquery.com/jquery-1.12.4.js"></script>
  <script src="//cdn.datatables.net/1.10.16/js/jquery.dataTables.min.js"></script>
  <script src="//cdn.datatables.net/1.10.16/js/dataTables.bootstrap4.min.js"></script>
  <script>
      $(document).ready(function() {
          $('#albums').DataTable({
              'serverSide': true,
              'ajax': '/api/albums/?format=datatables',
              'columns': [
                  {'data': 'rank'},
                  {'data': 'artist.name', 'name': 'artist.name'},
                  {'data': 'name'},
                  {'data': 'year'},
                  {'data': 'genres', 'name': 'genres.name'},
              ]

          });
      });
  </script>
</body>
</html>

Hint

Datatables uses the dot notation in the data field to populate columns with nested data. In this example, artist.name refers to the field name within the nested serializer artist.

Filtering

Filtering is based off of the either the data or name fields. If you need to filter on multiple fields, you can always pass through multiple variables like so

<script>
    'columns': [
        {'data': 'artist.name', 'name': 'artist.name, artist__year'}
</script>

This would allow you to filter the artist.name column based upon name or year.

Because the name field is used to filter on Django queries, you can use either dot or double-underscore notation as shown in the example above.

The values within a single name field are tied together using a logical OR operator for filtering, while those between name fields are strung together with an AND operator. This means that Datatables’ multicolumn search functionality is preserved.

If you need more complex filtering and ordering, you can always implement your own filter backend by inheriting from rest_framework_datatables.DatatablesFilterBackend.

Important

To sum up, for foreign keys and relations you need to specify a name for the column otherwise filtering and ordering will not work.

You can see this code live by running the example app.

Using DataTables via POST method

By default, the Ajax request that DataTables makes to obtain server-side processing data is an HTTP GET request. However, there are times when you might wish to use POST, DRF-Datatables can handle this, just configure your Datatable as explained in the related Datatables documentation section.

Handling Duplicates in Sorting

If sorting is done on a single column with more duplicates than the page size it’s possible than some rows are never retrieved as we traverse through our datatable. This is because of how order by together with limit and offset works in the database.

As a workaround for this problem we add a second column to sort by in the case of ties.

class AlbumViewSet(viewsets.ModelViewSet):
    queryset = Album.objects.all().order_by('year')
    serializer_class = AlbumSerializer
    datatables_additional_order_by = 'rank'

The example app

django-rest-framework-datatables comes with an example application (the Rolling Stone top 500 albums of all time). It’s a great start for understanding how things work, you can play with several options of Datatables, modify the python code (serializers, views) and test a lot of possibilities.

We encourage you to give it a try with a few commandline calls:

$ git clone https://github.com/izimobil/django-rest-framework-datatables.git
$ cd django-rest-framework-datatables
$ pip install -r requirements-dev.txt
$ python example/manage.py runserver
$ firefox http://127.0.0.1:8000

A screenshot of the example app:

Integration with Django-filter

django-rest-framework-datatables will always use icontains or iregex queries on all columns, which may be costly. More fine-grained control on the generated database queries can be achieved with Django-filter.

Integration with Django-filter is provided through Datatables-specific DatatablesFilterSet and DatatablesFilterBackend classes. These may be found in the django_filters subpackage.

Django-Filter Quickstart

Using the new DatatablesFilterBackend simply requires changing the import path. Instead of importing from rest_framework_datatables import from the django_filters subpackage.

from rest_framework_datatables.django_filters.backends import DatatablesFilterBackend
from rest_framework_datatables.django_filters.filterset import DatatablesFilterSet
from rest_framework_datatables.django_filters.filters import GlobalFilter

class GlobalCharFilter(GlobalFilter, filters.CharFilter):
    pass


class AlbumGlobalFilter(GlobalFilter):
    """Filter name, artist and genre by name with icontains"""

    name = GlobalCharFilter(lookup_expr='icontains')
    genres = GlobalCharFilter(field_name='genres__name', lookup_expr='icontains')
    artist = GlobalCharFilter(field_name='artist__name', lookup_expr='icontains')
    year = GlobalCharFilter()

    class Meta:
        model = Album
        fields = '__all__'


class AlbumGlobalViewSet(viewsets.ModelViewSet):
    queryset = Album.objects.all()
    serializer_class = AlbumSerializer
    filter_backends = (DatatablesFilterBackend,)
    filterset_class = AlbumGlobalFilter

Differences and Limitations

The data-data attribute or the columns[<n>][data] query parameter for the column must contain the name of the filter attribute on the filterset.

Although the DjangoFilterBackend uses the same parser for the queries generated by DataTables, the data-name attribute (or columns[<n>][name] query parameter) is completely ignored by the django-filter backend.

You can specify the lookup in the lookup_expr kwarg on the Filter. The ordering is implemented by looking at the field_name and lookup_expr attributes of the filters.

(Because of that, the keep parameter will not have the same semantics. It will cause the renderer to return the column, but it won’t be respected for global search by the backend and filterset. That means that only columns defined in the datatable can be filtered.)

The Django-Rest-Framework browsable api will not support global filters and the DataTables javascript frontend can’t take advantage of the automatic widgets generated by Django-filter.

Query Optimization

The above example will act as a drop-in replacement for the standard behaviour of django-rest-framework-datatables, which uses icontains and iregex for local and global queries.

With large tables this might generate very inefficient queries especially for non-string datatatypes.

By simply not using the GlobalFilter mixin, you can switch off global search per column to gain efficiency.

class AlbumGlobalFilter(AlbumFilter):
    """Filter name, artist and genre by name with icontains"""

    name = GlobalCharFilter(lookup_expr='icontains')
    genres = GlobalCharFilter(field_name='genres__name', lookup_expr='icontains')
    artist = GlobalCharFilter(field_name='artist__name', lookup_expr='icontains')

    class Meta:
        model = Album
        fields = '__all__'

This will revert the year field to the NumberFilter automatically generated by Django-filter which will require an exact number match.

Also you can use the capability of Django-filter to automatically generate the FilterSet for you:

class AlbumFilterViewSet(viewsets.ModelViewSet):
    queryset = Album.objects.all()
    serializer_class = AlbumSerializer
    filter_backends = [DatatablesFilterBackend]
    filterset_fields = '__all__'

In this case there will be no support for regular expressions, icontains or global searches, as Django-filter will use automatic lookups (e.g exact for strings), and you’ll need to add appropriate widgets to the datatable, because genres will need a multiple selection. It’s possible to use a javascript library such as yadcf to ease that task.

See the example app for an example of multiple selection using yadcf.

Customizing (global) queries

The defined filters will be used to filter the column search queries. Global queries are implemented with the optional global_q method on the GlobalFilter mixin. This will generate icontains or iregex lookups by default.

If you want more fine-grained control over queries, you can simply define your own filters.

Only filters that provide a global_q method will support global search queries.

The global_q method (as for example in the GlobalFilter mixin), should return a Q-object for the global field query. All these Q-objects will be combined with | (OR) and the resulting Q-object will be used used to filter the queryset that was returned by the applying the column filters.

This logic is identical to the one implemented by plain django-rest-framework-datatables.

Further Reading

It’s highly recommended to read the documentation of Django-filter.

Changelog

Version 0.6.0 (2021-02-09):

• Integration with django-filter
• Example of using yadcf and django-filter to create a multi-select column
• Fixed support for POST requests from datatables
• Some fixes on pagination

Many thanks to all the contributors on this release !

Version 0.5.2 (2020-04-10):

• Added support for POST requests from datatables
• Avoid extra count queries
• Handle dummy columns gracefully

Version 0.5.1 (2020-01-13):

• Added support for Django 3.0
• Added support for disabling pagination when the client requests it with length=-1 parameter
• Added optional column sorting to handle ties
• Minor code fixes

Version 0.5.0 (2019-03-31):

• Fixed total number of rows when view is using multiple filter back-ends
• New meta option datatables_extra_json on view for adding key/value pairs to rendered JSON
• Minor docs fixes

Version 0.4.1 (2018-11-16):

• Added support for Django 2.1 and DRF 3.9
• Updated README

Version 0.4.0 (2018-06-22):

• Added top level filtering for nested serializers
• Added multiple field filtering
• Added a ?keep= parameter that allows to bypass the filtering of unused fields
• Better detection of the requested format
• Fixed typo in Queryset.count() method name

Version 0.3.0 (2018-05-11):

• Added a serializer Meta option datatables_always_serialize that allows to specify a tuple of fields that should always be serialized in the response, regardless of what fields are requested in the Datatables request
• Optimize filters
• Use AND operator for column filtering instead of OR, to be consistant with the client-side behavior of Datatables

Version 0.2.1 (2018-04-11):

• This version replaces the 0.2.0 who was broken (bad setup.py)

Version 0.2.0 (2018-04-11):

• Added full documentation
• Removed serializers, they are no longer necessary, filtering of columns is made by the renderer

Version 0.1.0 (2018-04-10):

Initial release.

Useful links

• Github project page
• Bugtracker
• Documentation
• Pypi page