Add possibility to not perform redirect in set_language view on AJAX requests

[Krzysztof Jurewicz]

In set_language view, it should be possible to not perform redirect after request is made. Instead, a 204 status code could be returned. While performing a redirect was a reasonable behaviour in old times of HTML apps, for many AJAX applications it may be unnecessary and even uncomfortable if there is no good page become a redirect target.

[Krzysztof Jurewicz]

I’ve created a pull request: ​https://github.com/django/django/pull/1923

[Florian Apolloner]

I'd go even further, if there is no redirect parameter provided just return 204. Do all browsers etc support this properly?!

EDIT:// Thinking about this a bit more: since we change the language we have to redirect, how else would we change the UI?

[Krzysztof Jurewicz]

The project I’m currently working on uses Django as an API backend and AngularJS application as a frontend client to this API. The UI localization is done using Mozilla’s ​L20n project and language changing is done on-the-fly, without reloading the page. However there are some parts of the site which use Django templates (like password change form), so making an AJAX call to set_language is still necessary, but they are loaded using iframes, so there is no need to perform a redirect.

Not performing a redirect when it is not explicitly requested seems tempting, but it will be backwards incompatible with the current behaviour – I guess there may be a significant number of sites which rely on the fact that set_language redirects them to the previous page (captured from the referer header). Maybe we should check request.is_ajax() and if it is true, omit the redirect unless next parameter is set? For old-style HTML websites it may be still a coarsely correct assumption that a redirect needs to be performed after changing the language. That way we can resign from introducing the new no_redirect parameter.

204 status code seems to be supported by browsers, according to ​http://benramsey.com/blog/2008/05/http-status-204-no-content-and-205-reset-content/ .

[Aymeric Augustin]

This plan sounds good to me.

[Krzysztof Jurewicz]

I’ve updated the pull request accordingly.

[Tim Graham]

I left comments for improvement on PR. Please uncheck "Patch needs improvement" when you update it, thanks.

[Claude Paroz <claude@…>]

In 940b7fd5:

Fixed #21446 -- Allowed not performing redirect in set_language view

Thanks Claude Paroz and Tim Graham for polishing the patch.