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Parsers

Machine interacting web services tend to use more structured formats for sending data than form-encoded, since they’re sending more complex data than simple forms

‒ Malcom Tredinnick, Django developers group

REST framework includes a number of built in Parser classes, that allow you to accept requests with various media types. There is also support for defining your own custom parsers, which gives you the flexibility to design the media types that your API accepts.

How the parser is determined

The set of valid parsers for a view is always defined as a list of classes. When request.data is accessed, REST framework will examine the Content-Type header on the incoming request, and determine which parser to use to parse the request content.


Note: When developing client applications always remember to make sure you’re setting the Content-Type header when sending data in an HTTP request.

If you don’t set the content type, most clients will default to using 'application/x-www-form-urlencoded', which may not be what you wanted.

As an example, if you are sending json encoded data using jQuery with the .ajax() method, you should make sure to include the contentType: 'application/json' setting.


Setting the parsers

The default set of parsers may be set globally, using the DEFAULT_PARSER_CLASSES setting. For example, the following settings would allow only requests with JSON content, instead of the default of JSON or form data.

REST_FRAMEWORK = {
    'DEFAULT_PARSER_CLASSES': [
        'rest_framework.parsers.JSONParser',
    ]
}

You can also set the parsers used for an individual view, or viewset, using the APIView class-based views.

from rest_framework.parsers import JSONParser
from rest_framework.response import Response
from rest_framework.views import APIView

class ExampleView(APIView):
    """
    A view that can accept POST requests with JSON content.
    """
    parser_classes = [JSONParser]

    def post(self, request, format=None):
        return Response({'received data': request.data})

Or, if you’re using the @api_view decorator with function based views.

from rest_framework.decorators import api_view
from rest_framework.decorators import parser_classes
from rest_framework.parsers import JSONParser

@api_view(['POST'])
@parser_classes([JSONParser])
def example_view(request, format=None):
    """
    A view that can accept POST requests with JSON content.
    """
    return Response({'received data': request.data})

API Reference

JSONParser

Parses JSON request content. request.data will be populated with a dictionary of data.

.media_type: application/json

FormParser

Parses HTML form content. request.data will be populated with a QueryDict of data.

You will typically want to use both FormParser and MultiPartParser together in order to fully support HTML form data.

.media_type: application/x-www-form-urlencoded

MultiPartParser

Parses multipart HTML form content, which supports file uploads. Both request.data will be populated with a QueryDict.

You will typically want to use both FormParser and MultiPartParser together in order to fully support HTML form data.

.media_type: multipart/form-data

FileUploadParser

Parses raw file upload content. The request.data property will be a dictionary with a single key 'file' containing the uploaded file.

If the view used with FileUploadParser is called with a filename URL keyword argument, then that argument will be used as the filename.

If it is called without a filename URL keyword argument, then the client must set the filename in the Content-Disposition HTTP header. For example Content-Disposition: attachment; filename=upload.jpg.

.media_type: */*

Notes:

  • The FileUploadParser is for usage with native clients that can upload the file as a raw data request. For web-based uploads, or for native clients with multipart upload support, you should use the MultiPartParser instead.

  • Since this parser’s media_type matches any content type, FileUploadParser should generally be the only parser set on an API view.

  • FileUploadParser respects Django’s standard FILE_UPLOAD_HANDLERS setting, and the request.upload_handlers attribute. See the Django documentation for more details.

Basic usage example:

# views.py
class FileUploadView(views.APIView):
    parser_classes = [FileUploadParser]

    def put(self, request, filename, format=None):
        file_obj = request.data['file']
        # ...
        # do some stuff with uploaded file
        # ...
        return Response(status=204)

# urls.py
urlpatterns = [
    # ...
    re_path(r'^upload/(?P<filename>[^/]+)$', FileUploadView.as_view())
]

Custom parsers

To implement a custom parser, you should override BaseParser, set the .media_type property, and implement the .parse(self, stream, media_type, parser_context) method.

The method should return the data that will be used to populate the request.data property.

The arguments passed to .parse() are:

A stream-like object representing the body of the request.

Optional. If provided, this is the media type of the incoming request content.

Depending on the request’s Content-Type: header, this may be more specific than the renderer’s media_type attribute, and may include media type parameters. For example "text/plain; charset=utf-8".

Optional. If supplied, this argument will be a dictionary containing any additional context that may be required to parse the request content.

By default this will include the following keys: view, request, args, kwargs.

Example

The following is an example plaintext parser that will populate the request.data property with a string representing the body of the request.

class PlainTextParser(BaseParser):
    """
    Plain text parser.
    """
    media_type = 'text/plain'

    def parse(self, stream, media_type=None, parser_context=None):
        """
        Simply return a string representing the body of the request.
        """
        return stream.read()

Third party packages

The following third party packages are also available.

YAML

REST framework YAML provides YAML parsing and rendering support. It was previously included directly in the REST framework package, and is now instead supported as a third-party package.

Install using pip.

$ pip install djangorestframework-yaml

Modify your REST framework settings.

REST_FRAMEWORK = {
    'DEFAULT_PARSER_CLASSES': [
        'rest_framework_yaml.parsers.YAMLParser',
    ],
    'DEFAULT_RENDERER_CLASSES': [
        'rest_framework_yaml.renderers.YAMLRenderer',
    ],
}

XML

REST Framework XML provides a simple informal XML format. It was previously included directly in the REST framework package, and is now instead supported as a third-party package.

Install using pip.

$ pip install djangorestframework-xml

Modify your REST framework settings.

REST_FRAMEWORK = {
    'DEFAULT_PARSER_CLASSES': [
        'rest_framework_xml.parsers.XMLParser',
    ],
    'DEFAULT_RENDERER_CLASSES': [
        'rest_framework_xml.renderers.XMLRenderer',
    ],
}

MessagePack

MessagePack is a fast, efficient binary serialization format. Juan Riaza maintains the djangorestframework-msgpack package which provides MessagePack renderer and parser support for REST framework.

CamelCase JSON

djangorestframework-camel-case provides camel case JSON renderers and parsers for REST framework. This allows serializers to use Python-style underscored field names, but be exposed in the API as Javascript-style camel case field names. It is maintained by Vitaly Babiy.

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