WordPress Hooks

sending-emails-when-post-was-updated.php

<?php

/**
* See the following link to know the arguments passed by this action.
*
* @see https://developer.wordpress.org/reference/hooks/post_updated/
* @param int $post_ID - the post ID updated
* @param WP_Post $post_after - Post content after updated
* @param WP_Post $post_before - Post content before updated.
*/
function notify_users_that_post_was_updated( $post_ID, $post_after, $post_before ) {
  $users_email = array(
    'john@doe.com',
    'foo@bar.com',
    'juan@perez.com
  );
  
  // Let's prepare the email body.
  $body = sprintf( 
    'Hi all! This is a quick notification that the post %s was updated. <a href="%s">You can read it now</a>', 
    $post_after->post_title,
    get_the_permalink( $post_after )
   );
   
  /**
  * See the link to understand how the wp_mail function works
  *
  * @see https://developer.wordpress.org/reference/functions/wp_mail/
  */
  wp_mail(
    $users_email,
    "A post was updated in my amazing blog",
    $body
  );
}

/**
* Note that this action hook receives three params. So we need to let to WordPress
* know that we need to get the three arguments, otherwise it will broke.
*/
add_action( 'post_updated', 'notify_users_that_post_was_updated', 10, 3 );