I've been busy thinking about a problem, and so far I didn't find a solution to it.

The abstract scenario

On admin page A, I would like to print the value of a (global) variable—in the context of admin page B, though.

The concrete scenario

On a custom user-options page, I would like to list all metaboxes registered for each post type.

Both plugins and the theme can add/remove metaboxes with respect to the current page context ($pagenow). Thus, the $wp_meta_boxes global is set up in that context.

So far, I've read into virtually any hook, read a lot on AJAX (the right and the wrong ways), and tried out numerous different approaches I came up with. Unfortunatly, without luck.

The question

Is it possible to retrieve the value of $wp_meta_boxes on admin page post-new.php?post_type=my_super_duper_post_type, for instance, from another admin page?

If so, how would I go about that?

Can this be done via AJAX?
Or can I trick the plugins/theme into thinking that the current page is post-new.php?post_type=my_super_duper_post_type, for instance, while we're actually on my options page?

2 Answers 2


Ok, this could be achieved this way, probably.

add_action('add_meta_boxes_my_super_duper_post_type', 'get_metabox_global_ajax', 9999 );
function get_metabox_global_ajax(){
    if( isset($_GET['mgv']) && $_GET['mgv'] == '1' ){
        global $wp_meta_boxes;
        @error_reporting( 0 );
        header( 'Content-type: application/json' );
        die( json_encode( $wp_meta_boxes ));

Now, you send a request from your plugin page to post-new.php?post_type=my_super_duper_post_type&mgv=1 through ajax, and use the returned json response of wp_meta_boxeses variables.

  • Wow, thanks, that was quick. I will try this out and report back later (i.e., tomorrow). // Edit: Just for information, I never came across the add_meta_boxes_{$post_type} hook, so far. In case your complete answer shouldn't work, this is helpful nonetheless.
    – tfrommen
    Dec 11, 2013 at 16:16

Thanks to @Shazzad and @G.M., I found the right track.

Here is a short outline of what I did:

The JavaScript/AJAX action

jQuery(function($) {
    for (var i = 0; i < localizedData.postTypes.length; ++i) {
            type: 'post',
            url: 'post-new.php?post_type='+localizedData.postTypes[i],
            data: {
                action: 'my-plugin-action',
                _ajax_nonce: localizedData.nonce
            success: function(data) {
                if (data) {

Enqueue the JavaScript file for my custom user options page

$post_types = array(

if ('users' === basename($pagenow, '.php'))
    add_action('admin_print_scripts-users_page_my-plugin-page', 'MyPlugin_enqueue_scripts');

function MyPlugin_enqueue_scripts() {
    $data = array(
        'nonce' => wp_create_nonce('my_plugin_nonce'),
        'postTypes' => $post_types,
    $handle = 'my-plugin-js';
    wp_localize_script($handle, 'localizedData', $data);
} // function MyPlugin_enqueue_scripts

Set up the right hook to handle the AJAX request

global $pagenow;

if ('post-new' === basename($pagenow, '.php'))
    add_action('do_meta_boxes', 'MyPlugin_get_meta_boxes', PHP_INT_MAX);

function MyPlugin_get_meta_boxes($post_type) {
    if (
        'my-plugin-action' == filter_input(INPUT_POST, 'action')
        && in_array($post_type, $post_types)
    ) {

            'metaBoxes' => $GLOBALS['wp_meta_boxes']
} // function MyPlugin_get_meta_boxes

Now I am able to get all actually registered meta boxes for whatever post type I'd like—while being on some other admin page.

  • 1
    add_meta_boxes_'.$post_type run before do_meta_boxes. For me I'd used do_meta_boxes instead of using that high priority, adding action only once and moved the check for post type inside MyPlugin_get_meta_boxes, in fact do_meta_boxes pass post type as 1st argument. Then I'd used get_current_screen instead of rely on global $pagenow. And 2 tips: look at wp_send_json and use filter_input instead of direct access to $_POST and $_GET.
    – gmazzap
    Dec 18, 2013 at 8:06
  • @G.M. Thanks a lot for these suggestions. In fact, I never heard of wp_send_json before. And using do_meta_boxes with the post type as argument instead of using add_meta_boxes_{$post_type} makes much more sense, too. I just overlooked that I could specify the post type (meaning the page) for this hook. Thanks again.
    – tfrommen
    Dec 18, 2013 at 10:08
  • @tf Hi, I've a similar question about this stuff, do you know other way to access this without AJAX? here is my question wordpress.stackexchange.com/questions/154684/… Jul 15, 2014 at 19:05

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