XmlHttpRequest error: Origin null is not allowed b

Question

I'm developing a page that pulls images from Flickr and Panoramio via jQuery's AJAX support.

The Flickr side is working fine, but when I try to $.get(url, callback) from Panoramio, I see an error in Chrome's console:

XMLHttpRequest cannot load http://www.panoramio.com/wapi/data/get_photos?v=1&key=dummykey&tag=test&offset=0&length=20&callback=processImages&minx=-30&miny=0&maxx=0&maxy=150. Origin null is not allowed by Access-Control-Allow-Origin.

If I query that URL from a browser directly it works fine. What is going on, and can I get around this? Am I composing my query incorrectly, or is this something that Panoramio does to hinder what I'm trying to do?

Google didn't turn up any useful matches on the error message.

EDIT

Here's some sample code that shows the problem:

$().ready(function () {
  var url = 'http://www.panoramio.com/wapi/data/get_photos?v=1&key=dummykey&tag=test&offset=0&length=20&callback=processImages&minx=-30&miny=0&maxx=0&maxy=150';

  $.get(url, function (jsonp) {
    var processImages = function (data) {
      alert('ok');
    };

    eval(jsonp);
  });
});

You can run the example online.

EDIT 2

Thanks to Darin for his help with this. THE ABOVE CODE IS WRONG. Use this instead:

$().ready(function () {
  var url = 'http://www.panoramio.com/wapi/data/get_photos?v=1&key=dummykey&tag=test&offset=0&length=20&minx=-30&miny=0&maxx=0&maxy=150&callback=?';

  $.get(url, function (data) {
    // can use 'data' in here...
  });
});

Answer 1

In my case, same code worked fine on Firefox, but not on Google Chrome. Google Chrome's JavaScript console said:

XMLHttpRequest cannot load http://www.xyz.com/getZipInfo.php?zip=11234. 
Origin http://xyz.com is not allowed by Access-Control-Allow-Origin.
Refused to get unsafe header "X-JSON"

I had to drop the www part of the Ajax URL for it to match correctly with the origin URL and it worked fine then.

Answer 2

If you are doing local testing or calling the file from something like file:// then you need to disable browser security.

On MAC: open -a Google\ Chrome --args --disable-web-security

Answer 3

For the record, as far as I can tell, you had two problems:

1. You weren't passing a "jsonp" type specifier to your $.get, so it was using an ordinary XMLHttpRequest. However, your browser supported CORS (Cross-Origin Resource Sharing) to allow cross-domain XMLHttpRequest if the server OKed it. That's where the Access-Control-Allow-Origin header came in.

2. I believe you mentioned you were running it from a file:// URL. There are two ways for CORS headers to signal that a cross-domain XHR is OK. One is to send Access-Control-Allow-Origin: * (which, if you were reaching Flickr via $.get, they must have been doing) while the other was to echo back the contents of the Origin header. However, file:// URLs produce a null Origin which can't be authorized via echo-back.

The first was solved in a roundabout way by Darin's suggestion to use $.getJSON. It does a little magic to change the request type from its default of "json" to "jsonp" if it sees the substring callback=? in the URL.

That solved the second by no longer trying to perform a CORS request from a file:// URL.

To clarify for other people, here are the simple troubleshooting instructions:

1. If you're trying to use JSONP, make sure one of the following is the case:
   • You're using $.get and set dataType to jsonp.
   • You're using $.getJSON and included callback=? in the URL.
2. If you're trying to do a cross-domain XMLHttpRequest via CORS...
   1. Make sure you're testing via http://. Scripts running via file:// have limited support for CORS.
   2. Make sure the browser actually supports CORS. (Opera and Internet Explorer are late to the party)

Answer 4

We managed it via the http.conf file (edited and then restarted the HTTP service):

<Directory "/home/the directory_where_your_serverside_pages_is">
    Header set Access-Control-Allow-Origin "*"
    AllowOverride all
    Order allow,deny
    Allow from all
</Directory>

In the Header set Access-Control-Allow-Origin "*", you can put a precise URL.

Answer 5

For a simple HTML project:

cd project
python -m SimpleHTTPServer 8000

Then browse your file.

Answer 6

Not all servers support jsonp. It requires the server to set the callback function in it's results. I use this to get json responses from sites that return pure json but don't support jsonp:

function AjaxFeed(){

    return $.ajax({
        url:            'http://somesite.com/somejsonfile.php',
        data:           {something: true},
        dataType:       'jsonp',

        /* Very important */
        contentType:    'application/json',
    });
}

function GetData() {
    AjaxFeed()

    /* Everything worked okay. Hooray */
    .done(function(data){
        return data;
    })

    /* Okay jQuery is stupid manually fix things */
    .fail(function(jqXHR) {

        /* Build HTML and update */
        var data = jQuery.parseJSON(jqXHR.responseText);

        return data;
    });
}