Edit postmeta when user changes user role?

Question

I'm trying to update a postmeta field in the database called background-video. I want to clear the value from this when a user has changed the role to a user role called basic.

I found this code, which from what I understand runs when a user has changed role to the user role "basic".

add_action( 'basic', function( $user_id, $role, $old_roles ) 
{
    // Your code ...

}, 10, 3 );

The problem is I don't know how to target all the postmeta fields called background-video and clear the meta-value from them.

EDIT: I tried this, but it is not working:

add_action( 'set_user_role', function( $user_id, $role, $old_roles )
{
    if ( 'basic' == $role ) {


            $args = array( 'fields'          => 'ids',
                           'posts_per_page'  => -1,
                           'post_type'       => 'attachment',
                           'meta_key'        => 'background-video'
                           );
            $all_ids = new WP_Query( $args );

            foreach( $all_ids as $ai ) {

               update_post_meta( $ai->post->ID, 'background-video', '' );
            }
            wp_reset_postdata();


    }

}, 10, 3 );

Found the function here How can update custom meta for all posts

One other thing is that I use this on a WP Multisite, and I let the users select from a few different roles, but I want this function to fire when they select "basic".

Answer 1

Well, you're not entirely correct. This code will run, when the action called basic will be called using do_action('basic', ...). But... There is no such action in WP core, so your code won't run at all, I'm afraid.

There is hook that might be helpful in your case. It's called set_user_role and it has 3 params ($user_id, $role, $old_roles).

So your code should look more like this:

add_action( 'set_user_role', function( $user_id, $role, $old_roles ) 
{
    if ( 'basic' == $role ) {
        // Your code ...
    }

}, 10, 3 );