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I cannot get a cookie to set properly through WordPress theme. I am putting the following code on the bottom of my functions.php page for my theme.

function set_cookie() {
if (isset($_GET['id'])) {
    $referrerID = $_GET['id'];
        setcookie('referrerid', $referrerID,time()+ 3600 * 24, COOKIEPATH, COOKIE_DOMAIN, false);
add_action( 'init', 'set_cookie');

I even went as far as using JavaScript to alert if the script reached the function (which it did).

Why are my cookies not being set?? (The code works locally - outside of WordPress that is).

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1 Answer 1

up vote 1 down vote accepted

Make sure the HTTP headers are not sent already at the point you want to set the cookie. Here's how you can test that:

function set_cookie() {
  var_dump(headers_sent()); // should be bool(false)

Turning WP_DEBUG on in your config.php file may help also while debugging.

By the way, you really should be doing some filtering on $_GET['id']. This variable could contain anything. Casting it to a (positive) integer should go a long way:

$referrerID = absint($_GET['id']); // Note: absint() is a WP function
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I can place that function anywhere and how will it let me know the results? Does it echo the information back? –  Evan Jan 19 '12 at 13:25
Yes, var_dump() echoes its output. –  Geert Jan 19 '12 at 14:04
it returned bool(false) - the cookie is still not being set though. Is there any way we could do a private chat if you have a free minute? –  Evan Jan 19 '12 at 14:05
Not possible now. Could you inspect the HTTP response headers? Look for the Set-Cookie header. –  Geert Jan 19 '12 at 14:15
What would be the best way to go about retrieving such headers? I used this code just now but I don't think it's what you were looking for: foreach (getallheaders() as $name => $value) { echo "$name: $value\n"; } –  Evan Jan 19 '12 at 14:21

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