7.0 KiB
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 either request.DATA or request.FILES 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 requests with YAML content.
REST_FRAMEWORK = {
'DEFAULT_PARSER_CLASSES': (
'rest_framework.parsers.YAMLParser',
)
}
You can also set the renderers used for an individual view, or viewset,
using the APIView class based views.
class ExampleView(APIView):
"""
A view that can accept POST requests with YAML content.
"""
parser_classes = (YAMLParser,)
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.
@api_view(['POST'])
@parser_classes((YAMLParser,))
def example_view(request, format=None):
"""
A view that can accept POST requests with YAML content.
"""
return Response({'received data': request.DATA})
API Reference
JSONParser
Parses JSON request content.
.media_type: application/json
YAMLParser
Parses YAML request content.
Requires the pyyaml package to be installed.
.media_type: application/yaml
XMLParser
Parses REST framework's default style of XML request content.
Note that the XML markup language is typically used as the base language for more strictly defined domain-specific languages, such as RSS, Atom, and XHTML.
If you are considering using XML for your API, you may want to consider implementing a custom renderer and parser for your specific requirements, and using an existing domain-specific media-type, or creating your own custom XML-based media-type.
Requires the defusedxml package to be installed.
.media_type: application/xml
FormParser
Parses HTML form content. request.DATA will be populated with a QueryDict of data, request.FILES will be populated with an empty 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 and request.FILES 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
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:
stream
A stream-like object representing the body of the request.
media_type
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".
parser_context
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()
Uploading file content
If your custom parser needs to support file uploads, you may return a DataAndFiles object from the .parse() method. DataAndFiles should be instantiated with two arguments. The first argument will be used to populate the request.DATA property, and the second argument will be used to populate the request.FILES property.
For example:
class SimpleFileUploadParser(BaseParser):
"""
A naive raw file upload parser.
"""
media_type = '*/*' # Accept anything
def parse(self, stream, media_type=None, parser_context=None):
content = stream.read()
name = 'example.dat'
content_type = 'application/octet-stream'
size = len(content)
charset = 'utf-8'
# Write a temporary file based on the request content
temp = tempfile.NamedTemporaryFile(delete=False)
temp.write(content)
uploaded = UploadedFile(temp, name, content_type, size, charset)
# Return the uploaded file
data = {}
files = {name: uploaded}
return DataAndFiles(data, files)
Third party packages
The following third party packages are also available.
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.