PHP Cookies returning empty from jQuery/Ajax call

Question

I have a domain (example.com) that sets a cookie using PHP like so:

$source = 123;
setcookie("source", $source, time()+3600, '/', ".example.com");

I want to share this cookie across sub-domains. When I navigate to "sub.example.com/index.php" and run the following PHP code:

echo $_COOKIE['source'];

...I get the correct output: 123. Good!

The problem I have is that when I make an ajax call using jQuery to "sub.example.com", the cookie doesn't output. It's empty.

$.ajax({
  type: "POST",
  url: 'http://sub.example.com/index.php',
  dataType: "text",
  error: function(jqXHR,textStatus,errorThrown) {

  },
  success: function() {
   // DOES SOMETHING

  }
});

Is there something I don't know about ajax and cookies across subdomains?

(I'm aware the above Ajax call doesn't do anything. In my real-life code, the page on the sub-domain writes the COOKIE value to a database. When I load the page directly in my browser, the database is correctly updated. When I load the page from ajax, the database entry is updated but all values are empty.)

If ajax and jquery have security issues across sub domains, you can just echo the cookie info into a var on page load instead. — Gary Hayes, Nov 04 '13 at 23:24
@Gary Hayes - But the cookies are outputed if I load the subdomain page directly. So the cookies are definitely set. — Andrew, Nov 04 '13 at 23:26
possible duplicate of [cookies problem in PHP and AJAX](http://stackoverflow.com/questions/6353782/cookies-problem-in-php-and-ajax) — nietonfir, Nov 04 '13 at 23:26
@nietonfir - I'm using the '/' for global path so it's not the same problem... — Andrew, Nov 04 '13 at 23:28

score 1 · Answer 1 · answered Nov 04 '13 at 23:40

In the end, the problem was the ajax call. Because it was crossdomain (or across subdomains), the answer was in the xhrFields param (http://api.jquery.com/jQuery.ajax/).

$.ajax({
  type: "POST",
  url: 'http://sub.example.com/index.php',
  dataType: "text",
  xhrFields: {
      withCredentials: true
   }
  error: function(jqXHR,textStatus,errorThrown) {
  },
  success: function() {
   // DOES SOMETHING
  }
});

PHP Cookies returning empty from jQuery/Ajax call

1 Answers1