Getting List of all registered Dashboard Widgets

Question

I am trying to get a list of all registered meta boxes in the wordpress admin, specifically the Dashboard widgets.

Now this is easily achieved with the global variable $wp_meta_boxes and does exactly what I need but only when on the dashboard page.

If I am on a custom admin page or a setting page for example, I get nothing. I am trying to get a list of dashboard widgets and give users the option to put them on a different custom admin page / dashboard.

There are a couple of other similar questions to getting these meta boxes and I am aware of the following code that is been given as an answer, however it has the same problem and it returns an empty array if not on the dashboard page:

function get_meta_boxes( $screen = null, $context = 'advanced' ) {
    global $wp_meta_boxes;

    if ( empty( $screen ) )
        $screen = get_current_screen();
    elseif ( is_string( $screen ) )
        $screen = convert_to_screen( $screen );

    $page = $screen->id;

    return $wp_meta_boxes[$page][$context];
}

Anyone have any ideas? Should the $wp_meta_boxes be working and there is something going on with my setup? Or is there another way of doing this?

Any help would be massively appreciated!

Answer 1

The reason for this is that dashboard widgets don't use the metabox API directly, they use an API that wraps around it, and are only registered on wp_dashboard_setup and wp_network_dashboard_setup.

They're also named dashboard widgets rather than metaboxes, so most users will not know what you're referring to if you talk about metaboxes. Dashboard metaboxes could refer to any metabox in WP Admin.

This means on your custom admin page, those hooks don't fire, resulting in the global variable not containing dashboard widgets.

Additionally, the default WP widgets don't display themselves via those hooks, but instead are added in the same function that displays the dashboard itself, wp_dashboard_setup. This function registers the core dashboard widgets, fires the hooks for plugins to add their own, then triggers the metabox API to display them.

So you would need to:

• call wp_dashboard_setup on your custom pages
• move your code to the wp_dashboard_setup hook, and make sure it runs last/late
• add and remove widgets according to the options you set

It may be easier to remove and replace the main dashboard UI completely, the API was never intended to be used for what you're trying to do with it.

Just keep in mind that the screen options UI will not reflect your changes, and might actively interfere with what you're doing.