Django CSRF check failing with an Ajax POST request

ghz 1years ago ⋅ 8318 views

Question

I could use some help complying with Django's CSRF protection mechanism via my AJAX post. I've followed the directions here:

http://docs.djangoproject.com/en/dev/ref/contrib/csrf/

I've copied the AJAX sample code they have on that page exactly:

http://docs.djangoproject.com/en/dev/ref/contrib/csrf/#ajax

I put an alert printing the contents of getCookie('csrftoken') before the xhr.setRequestHeader call and it is indeed populated with some data. I'm not sure how to verify that the token is correct, but I'm encouraged that it's finding and sending something.

But Django is still rejecting my AJAX post.

Here's my JavaScript:

$.post("/memorize/", data, function (result) {
    if (result != "failure") {
        get_random_card();
    }
    else {
        alert("Failed to save card data.");
    }
});

Here's the error I'm seeing from Django:

[23/Feb/2011 22:08:29] "POST /memorize/ HTTP/1.1" 403 2332

I'm sure I'm missing something, and maybe it's simple, but I don't know what it is. I've searched around SO and saw some information about turning off the CSRF check for my view via the csrf_exempt decorator, but I find that unappealing. I've tried that out and it works, but I'd rather get my POST to work the way Django was designed to expect it, if possible.

Just in case it's helpful, here's the gist of what my view is doing:

def myview(request):

    profile = request.user.profile

    if request.method == 'POST':
        """
        Process the post...
        """
        return HttpResponseRedirect('/memorize/')
    else: # request.method == 'GET'

        ajax = request.GET.has_key('ajax')

        """
        Some irrelevent code...
        """

        if ajax:
            response = HttpResponse()
            profile.get_stack_json(response)
            return response
        else:
            """
            Get data to send along with the content of the page.
            """

        return render_to_response('memorize/memorize.html',
                """ My data """
                context_instance=RequestContext(request))

Thanks for your replies!

Answer

Real solution

Ok, I managed to trace the problem down. It lies in the Javascript (as I suggested below) code.

What you need is this:

$.ajaxSetup({ 
     beforeSend: function(xhr, settings) {
         function getCookie(name) {
             var cookieValue = null;
             if (document.cookie && document.cookie != '') {
                 var cookies = document.cookie.split(';');
                 for (var i = 0; i < cookies.length; i++) {
                     var cookie = jQuery.trim(cookies[i]);
                     // Does this cookie string begin with the name we want?
                     if (cookie.substring(0, name.length + 1) == (name + '=')) {
                         cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
                         break;
                     }
                 }
             }
             return cookieValue;
         }
         if (!(/^http:.*/.test(settings.url) || /^https:.*/.test(settings.url))) {
             // Only send the token to relative URLs i.e. locally.
             xhr.setRequestHeader("X-CSRFToken", getCookie('csrftoken'));
         }
     } 
});

instead of the code posted in the official docs: https://docs.djangoproject.com/en/2.2/ref/csrf/

The working code, comes from this Django entry: http://www.djangoproject.com/weblog/2011/feb/08/security/

So the general solution is: "use ajaxSetup handler instead of ajaxSend handler". I don't know why it works. But it works for me :)

Previous post (without answer)

I'm experiencing the same problem actually.

It occurs after updating to Django 1.2.5 - there were no errors with AJAX POST requests in Django 1.2.4 (AJAX wasn't protected in any way, but it worked just fine).

Just like OP, I have tried the JavaScript snippet posted in Django documentation. I'm using jQuery 1.5. I'm also using the "django.middleware.csrf.CsrfViewMiddleware" middleware.

I tried to follow the the middleware code and I know that it fails on this:

request_csrf_token = request.META.get('HTTP_X_CSRFTOKEN', '')

and then

if request_csrf_token != csrf_token:
    return self._reject(request, REASON_BAD_TOKEN)

this "if" is true, because "request_csrf_token" is empty.

Basically it means that the header is NOT set. So is there anything wrong with this JS line:

xhr.setRequestHeader("X-CSRFToken", getCookie('csrftoken'));

?

I hope that provided details will help us in resolving the issue :)

#django