django-rest-framework/docs/topics/browser-enhancements.md

Browser enhancements

"There are two noncontroversial uses for overloaded POST. The first is to simulate HTTP's uniform interface for clients like web browsers that don't support PUT or DELETE"

— RESTful Web Services, Leonard Richardson & Sam Ruby.

In order to allow the browsable API to function, there are a couple of browser enhancements that REST framework needs to provide.

As of version 3.3.0 onwards these are enabled with javascript, using the ajax-form library.

Browser based PUT, DELETE, etc...

The AJAX form library supports browser-based PUT, DELETE and other methods on HTML forms.

After including the library, use the data-method attribute on the form, like so:

<form action="/" data-method="PUT">
    <input name='foo'/>
    ...
</form>

Note that prior to 3.3.0, this support was server-side rather than javascript based. The method overloading style (as used in Ruby on Rails) is no longer supported due to subtle issues that it introduces in request parsing.

Browser based submission of non-form content

Browser-based submission of content types such as JSON are supported by the AJAX form library, using form fields with data-override='content-type' and data-override='content' attributes.

For example:

    <form action="/">
        <input data-override='content-type' value='application/json' type='hidden'/>
        <textarea data-override='content'>{}</textarea>
        <input type="submit"/>
    </form>

Note that prior to 3.3.0, this support was server-side rather than javascript based.

URL based format suffixes

REST framework can take ?format=json style URL parameters, which can be a useful shortcut for determining which content type should be returned from the view.

This behavior is controlled using the URL_FORMAT_OVERRIDE setting.

HTTP header based method overriding

Prior to version 3.3.0 the semi extension header X-HTTP-Method-Override was supported for overriding the request method. This behavior is no longer in core, but can be adding if needed using middleware.

For example:

METHOD_OVERRIDE_HEADER = 'HTTP_X_HTTP_METHOD_OVERRIDE'

class MethodOverrideMiddleware(object):
    def process_view(self, request, callback, callback_args, callback_kwargs):
        if request.method != 'POST':
            return
        if METHOD_OVERRIDE_HEADER not in request.META:
            return
        request.method = request.META[METHOD_OVERRIDE_HEADER]

URL based accept headers

Until version 3.3.0 REST framework included built-in support for ?accept=application/json style URL parameters, which would allow the Accept header to be overridden.

Since the introduction of the content negotiation API this behavior is no longer included in core, but may be added using a custom content negotiation class, if needed.

For example:

class AcceptQueryParamOverride()
    def get_accept_list(self, request):
       header = request.META.get('HTTP_ACCEPT', '*/*')
       header = request.query_params.get('_accept', header)
       return [token.strip() for token in header.split(',')]

Doesn't HTML5 support PUT and DELETE forms?

Nope. It was at one point intended to support PUT and DELETE forms, but was later dropped from the spec. There remains ongoing discussion about adding support for PUT and DELETE, as well as how to support content types other than form-encoded data.