javascript - therefore - the 'access-control-allow-origin' header has a value 'null' that is not equal to the supplied origin




XmlHttpRequest error: Origin null is not allowed by Access-Control-Allow-Origin (11)

As final note the Mozilla documentation explicitly says that

The above example would fail if the header was wildcarded as: Access-Control-Allow-Origin: *. Since the Access-Control-Allow-Origin explicitly mentions http://foo.example, the credential-cognizant content is returned to the invoking web content.

As consequence is a not simply a bad practice to use '*'. Simply does not work :)

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...
  });
});

As long as the requested server supports the JSON data format, use the JSONP (JSON Padding) interface. It allows you to make external domain requests without proxy servers or fancy header stuff.


For a simple HTML project:

cd project
python -m SimpleHTTPServer 8000

Then browse your file.


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)

I use Apache server, so I've used mod_proxy module. Enable modules:

LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so

Then add:

ProxyPass /your-proxy-url/ http://service-url:serviceport/

Finally, pass proxy-url to your script.


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


It's the same origin policy, you have to use a JSON-P interface or a proxy running on the same host.


Make sure you are using the latest version of JQuery. We were facing this error for JQuery 1.10.2 and the error got resolved after using JQuery 1.11.1


There is a small problem in the solution posted by CodeGroover above , where if you change a file, you'll have to restart the server to actually use the updated file (at least, in my case).

So searching a bit, I found this one To use:

sudo npm -g install simple-http-server # to install
nserver # to use

And then it will serve at http://localhost:8000.


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.


You need to maybe add a HEADER in your called script, here is what I had to do in PHP:

header('Access-Control-Allow-Origin: *');

More details in Cross domain AJAX ou services WEB (in French).





jsonp