django-rest-framework/docs/topics/browser-enhancements.md
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# 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][cite], 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][ajax-form] library.
## Browser based PUT, DELETE, etc...
The [AJAX form library][ajax-form] 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][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][ajax-form], 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][html5]. There remains
[ongoing discussion][put_delete] about adding support for `PUT` and `DELETE`,
as well as how to support content types other than form-encoded data.
[cite]: http://www.amazon.com/Restful-Web-Services-Leonard-Richardson/dp/0596529260
[ajax-form]: https://github.com/encode/ajax-form
[rails]: http://guides.rubyonrails.org/form_helpers.html#how-do-forms-with-put-or-delete-methods-work
[html5]: http://www.w3.org/TR/html5-diff/#changes-2010-06-24
[put_delete]: http://amundsen.com/examples/put-delete-forms/