I'm trying to integrate ajax in wordpress using the wp codex guidelines. In the PHP I added:

wp_enqueue_script ( 'my_ajax', ADMIN_URL . 'js/ajax.js','jquery','1.0.0' );
wp_localize_script( 'my_ajax', 'MyAjax', array( 'ajaxurl' => admin_url( 'admin-ajax.php' ) ) );

The ajax code is:

jQuery.ajax({url: MyAjax.ajaxurl, type: "POST",data: {action: 'myaction',postID : MyAjax.postID}, success: function(response) {
 alert('Got this from the server: ' + response);

and the PHP function that should be called by ajax is:

function ajax_function() {
...do something...
add_action('wp_ajax_myaction', 'ajax_function');
add_action('wp_ajax_admin_myaction', 'ajax_function');

The ajax call is successful (the "alert" works), however, the php function "ajax_function" is never called. After doing some debugging I realized that even though the action call add_action('wp_ajax_ sets a new element in the global $wp_filter array, when the corresponding do_action runs inside admin-ajax.php, the $wp_filter array no longer contains that element.

Therefore, "ajax_function" function is ignored. Any idea why the function is not called?

  • @user1567: You add the function to the wp_ajax_myaction and wp_ajax_admin_myaction hooks. Should that not be wp_ajax_myaction (for logged in users) and wp_ajax_nopriv_myaction (for anonymous users)?
    – Jan Fabry
    Commented Dec 1, 2010 at 13:52
  • yes I fixed it, thanks. By the way, I have an update_option call inside the "ajax_function" that seem to fail because it is called after all wordpress loading sequence is complete? Is there another way to update_option?
    – user1567
    Commented Dec 1, 2010 at 16:26

2 Answers 2


In my projects I do it like that


function foo() {
    echo 'bar';
add_action('wp_ajax_foo', 'foo' ); // executed when logged in
add_action('wp_ajax_nopriv_foo', 'foo' ); // executed when logged out


data = { action: 'foo', avalue: 'some value', 'anothervalue': 'another value' };
jQuery.post(ajaxurl, data, function(response){
  • 1
    Thanks for the answer. I know this guide, I went over it as well. I changed the function to be exactly like yours but no luck :-( The function is still not called.
    – user1567
    Commented Dec 1, 2010 at 12:43
  • by the way, where do you set the value of ajaxurl variable?
    – user1567
    Commented Dec 1, 2010 at 12:46
  • 1
    In my example I assumed that variable is already set. In WP Backend the variable is always set. In the frontend I just define it in the header. <script type="text/javascript"> var ajaxurl = <?php bloginfo('url') ?>'/wp-admin/admin-ajax.php'; </script> I bet there is a smarter way to handle it.
    – Horttcore
    Commented Dec 1, 2010 at 13:46
  • I see. anyway, the function still doesn't work for me. Does it matter that the ajax is for admin back end? or the same functions should be used?
    – user1567
    Commented Dec 1, 2010 at 14:35
  • I finally fixed it. The problem was the loading order and the location of the add_action calls. I have another small question: you wrote data = { action: 'foo', avalue: 'some value', 'anothervalue': 'another value' }; What if I want to include an array as the value of one of the keys?
    – user1567
    Commented Dec 1, 2010 at 15:23

Please follow the code:

add_action( 'wp_ajax_add_myfunc', 'prefix_ajax_add_myfunc' );
add_action( 'wp_ajax_nopriv_add_myfunc', 'prefix_ajax_add_myfunc' );

function prefix_ajax_add_myfunc() {
    // Handle request then generate response using WP_Ajax_Response

and in your ajax call do this:

        'action': 'add_myfunc',
        'data':   'foobarid'
        alert('The server responded: ' + response);

in the ajax call you'll call your function without prefix_ajax_. Only call by it's remaining. In that case it's add_myfunc. In the response it will send done if everything goes right. Else response will be 0 or -1.

Hope it will help. Thank you.

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