Friday, May 6, 2011

Django, jQuery, XMLHttpResponse error

I'm trying to learn some basic ajax using Django. My simple project is an app that randomly selects a Prize from the available prizes in the database, decrements its quantity, and returns to the page.

I'm using jQuery's $.ajax method to pull this off. The the only thing that's running is the error function defined in my $.ajax call, but the error message says nothing but "error". I'm new to ajax, so I'm probably overlooking something obvious. Here's the relevant code:


class Prize(models.Model):
    name = models.CharField(max_length=50)
    quantity = models.IntegerField(default=0)

    def __unicode__(self):


urlpatterns = patterns('',
    (r'^get_prize/$', 'app.views.get_prize' ),


def get_prize(request):
    prizes = Prize.objects.filter(quantity__gt=0)
    to_return = {}

    if prizes:
         rand = random.randrange(len(prizes))
     prize = prizes[rand]
     prize.quantity -= 1

     to_return['prize'] =
     data = simplejson.dumps(to_return)

     return HttpResponse(data, mimetype='application/json')

     to_return['msg'] = "That's all the prizes.  No more."
     data = simplejson.dumps(to_return)

     return HttpResponse(data, mimetype='application/json')


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "">
<html xmlns="">
<title>User's Conference Prize Randomizer</title>
<link rel="stylesheet" type="text/css" href="/static-media/style.css" />
<script type="text/javascript" src="/static-media/jquery-1.2.6.min.js"></script>

<script type="text/javascript">
 var get_prize = function() {
  var args = { 
   type: "GET",
   url: "get_prize",
   dataType: "json",
   success: done,
   error: function(response,error_string,e){
    alert( "Error: " + response.responseText + " " + error_string ); 
    for (i in e){


 var done = function(response) {
  if(response) {

  else {
   alert("Something boo-booed");

 $(document).ready(function() {

</head >

        <p><a href="" id='start'>Get Prize</a>, this link isn't working how I'd like.</p>


From stackoverflow
  • This is not a direct answer to your question, but have you looked at the jQuery taconite plugin? It makes most AJAXy stuff trivial to do. More on malup's taconite page. While you're at it, checkout his other excellent plugins.

  • Good grief. I had just left out return false in the function that made the ajax call. Way to go n00b. :0.

  • This isn't exactly related to your question, but if you're trying to fetch a random object from the database, you could do this instead:

    prize = Prize.objects.filter(quantity__gt=0).order_by('?')[:1]
    if prize:
        prize = prize[0]
    # Using a slice prevents an exception if the query returns an empty queryset.
    # If you're not a fan of LBYL, you could wrap the query in a try...except block instead:
        prize = Prize.objects.filter(quantity__gt=0).order_by('?')[0]
    except IndexError:
        # No more prizes pal...done, fini.


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