AJAX: Dynamically modifying the options.dataType in an ajaxPrefilter doesn't trigger the correct ajax converter.

[ralphholzmann]

I'm writing an app against a backend that I don't have access to. The backend is returning data in the wrong format, so I need to modify the data returned from the server for every request before it passes it along to the ajax success callback.

So I set up an ajax converter that will make the necessary modifications under the dataType "json fix", and it works great! \o/.

However, rather than go through my entire app and change the dataType for each ajax request, I thought it would be easier to set up an ajax prefilter that checks if the dataType is json, and if it is, adds " fix" to the dataType, thus triggering the converter. Unfortunately, this doesn't work. It works fine if I have the dataType originally set to "json fix", but dynamically adding it via an ajax prefilter does not work. :(

Test case: ​http://jsfiddle.net/DtpsB/1/

[jaubourg]

That's because modifying options.dataType won't do a thing: $.ajax() already split it as an array. You can simply toy with the actual internal array, options.dataTypes:

​http://jsfiddle.net/FdGzS/

Please note that you can specify the dataType for which your prefilter is to be executed (which is spot on in your use case).