Custom post type submenu sorted by specific meta_key & meta_value

Question

I have a created a custom post type called "Events" using register_post_type. I am now trying to create a submenu within "Events" that will only show events sorted by a specific meta_key and meta_value. (Example: Only show events that have been marked as "priority.")

I am using this code to create the "priority events" submenu, but the query continues to return all of my events instead of just the priority events:

function rt_priority_event_add_submenu() {

$sub_slug = 'edit.php?post_type=event&meta_key=event_priority&meta_value=true';
add_submenu_page('edit.php?post_type=event', 'Priority Events', 'Priority Events', 'manage_options', $sub_slug); 

}

Here is the Events custom post type is set up:

register_post_type( 'event', array(
        'label' => 'Events',
        'labels' => rt_ui_labels( 'Event', 'Events', 'redtri' ),
        'public' => true,
        'has_archive' => true,
        'rewrite' => true,
        'supports' => array( 'title', 'editor', 'excerpt', 'thumbnail'),
    ) );

I don't need any new fancy columns or anything - I just want to use the same columns already set up in Events.

Thanks in advance, and please let me know if you need more information!

Answer 1

Meta key or meta value in query parameter doesn't automatically filter the query by default. So you have to filter the query to restrict results.

add_filter('pre_get_posts', 'restrict_events_by_meta');
function restrict_events_by_meta($q){
    if( 
        $q->is_main_query() 
        && is_admin() 
        && 'event' == $q->get('post_type') 
        && isset( $_GET['meta_key']) 
        && isset( $_GET['meta_value']) 
    ){
        $q->set('meta_key', $_GET['meta_key'] );
        $q->set('meta_value', $_GET['meta_value'] );
        $q->set('orderby', 'meta_key' );
    }
}