Send Emails to Wordpress Users on Post Publish and Update - wordpress

Question

I have managed to send users an email when a post is published using transition_post_status, but it does not send when the post is updated. I have tried using 'new' with both old_status and new_status but no luck. Any direction is greatly appreciated. My reference thus far is from https://wordpress.stackexchange.com/questions/100644/how-to-auto-send-email-when-publishing-a-custom-post-type?rq=1
add_action('transition_post_status', 'send_media_emails', 10, 3);
function send_media_emails($new_status, $old_status, $post){
if ( 'publish' !== $new_status or 'publish' === $old_status)
return;
$the_media = get_users( array ( 'role' => 'media' ) );
$emails = array ();
foreach($the_media as $media)
$emails[] = $media->user_email;
$body = sprintf('There are new bus cancellations or delays in Huron-Perth <%s>', get_permalink($post));
wp_mail($emails, 'New Bus Cancellation or Delay', $body);
}
//Working but sending double emails now. I tried wrapping it all in the function but that didn't work either. just confused as to where to put it.
function send_media_emails($post_id){
$the_media = get_users( array ( 'role' => 'media' ) );
$emails = array ();
if( ! ( wp_is_post_revision( $post_id) && wp_is_post_autosave( $post_id ) ) ) {
return;
}
if(get_post_status($post_id) == 'draft' or get_post_status($post_id) == 'pending' or get_post_status($post_id) == 'trash'){
return;
}
foreach($the_media as $media){
$emails = $media->user_email;
}
$body = sprintf('There are new bus cancellations or delays in Huron-Perth <%s>', get_permalink($post_id));
wp_mail($emails, 'New Bus Cancellation or Delay', $body);
}
add_action('post_updated', 'send_media_emails');

Answer 1

The transition_post_status hook only fires when the post status changes, e.g. from 'Draft' to 'Publish'.
A better hook would be post_updated. This fires on all updates, so you'll need to filter out updates to drafts and comments in your script.
You might be able to do a 'publish_to_publish' action, but I haven't tested this personally.

Answer 2

transition_post_status will also fire when a post is updated (publish > publish for example).
However, a known bug makes transition_post_status sometimes fire twice: https://github.com/WordPress/gutenberg/issues/15094
There's a solution for the double firing of transition_post_status, which I copy from there:
function ghi15094_my_updater( $new_status, $old_status, $post ) {
// run your code but do NOT count on $_POST data being available here!
}
function ghi15094_transition_action( $new_status, $old_status, $post ) {
if ( defined( 'REST_REQUEST' ) && REST_REQUEST ) {
ghi15094_my_updater( $new_status, $old_status, $post );
set_transient( 'my_updater_flag', 'done', 10 );
} else {
if ( false === get_transient( 'my_updater_flag' ) ) {
ghi15094_my_updater( $new_status, $old_status, $post );
}
}
}
add_action( 'transition_post_status', 'ghi15094_transition_action', 10, 3 );