Changing post content on save, using updated fields

Question

Short:

I want to change the post's slug (for permalink purposes) upon saving, and use data I just entered in the post editor to modify it.

Long:

I am currently using the Tribe Events Calendar plug-in, and want to create multiple events with the same title, so to make sure the permalinks are unique, I add the event date (which is stored alongside the post) to the end of the slug on saving the event (post).

What I have done so far

I have the permalink update working by using the save_post hook:

function change_event_slug_on_save( $post_id ) {
    if ( ! wp_is_post_revision( $post_id ) && tribe_is_event($post_id) ) {
        // verify post is not a revision, and an event
        $post = get_post($post_id);
        $slug = sanitize_title($post->post_title);
        $newslug = $slug . '-' . tribe_get_start_date( $post_id, false, 'j F Y' );
        if ($post->post_name !== $newslug) {
            // unhook this function to prevent infinite looping
            remove_action( 'save_post', 'change_event_slug_on_save' );
            // update the post slug
            wp_update_post( array(
                'ID' => $post_id,
                'post_name' => $newslug
            ));
            // re-hook this function
            add_action( 'save_post', 'change_event_slug_on_save', 10, 1 );
        }
    }
}

add_action( 'save_post', 'change_event_slug_on_save', 10, 1 );

The problem

When I change the event's date, I of course want to update the permalink as well. The trouble is: the event date that I just changed, has not yet been changed in the database, so when updating the permalink on save_post, it still uses the last stored (old) event date. This means I need to save an event (post) twice to update the link.

I have tried hooking to pre_update_post, but that gives me the same problem. I have also looked into all the hooks Tribe plug-in offers, but found none that offers to hook into an update event.

Bottom line: I need to find a way to update the permalink when the post editor's fields are updated (before actually publishing or updating a post), using the fields as they are at the time (and not coming from the database). Any help would be very much appreciated.

---

UPDATE

Thanks to ahendwh2's answer I fixed it, by hooking into Tribe's tribe_events_update_meta hook, the updated code:

function change_event_slug_on_save( $post_id, $event_data, $event ) {
    //$event_data holds the changed event data, $event is the actual event (post)
    if ( ! wp_is_post_revision( $post_id ) && tribe_is_event($post_id) ) {
        // verify post is not a revision, and an event
        $slug = sanitize_title($event->post_title);
        $newslug = $slug . '-' . tribe_format_date($event_data['EventStartDate'], false, 'j-F-Y');
        if ($event->post_name !== $newslug) {
            // unhook this function to prevent infinite looping
            remove_action( 'tribe_events_update_meta', 'change_event_slug_on_save' );
            // update the post slug
            wp_update_post( array(
                'ID' => $post_id,
                'post_name' => $newslug
            ));
            // re-hook this function
            add_action( 'tribe_events_update_meta', 'change_event_slug_on_save', 10, 3 );
        }
    }
}
add_action( 'tribe_events_update_meta', 'change_event_slug_on_save', 10, 3);

Answer 1

Try to use the post object provided by the action as the second parameter instead of getting it from database:

function change_event_slug_on_save( $post_id, $post ) {
    ...
}

add_action( 'save_post', 'change_event_slug_on_save', 10, 2 );

With this you can remove the line $post = get_post($post_id);

---

EDIT: Tribe Events Calendar has it's own actions for saving an event: tribe_events_event_save and tribe_events_update_meta. Since the event date is saved in post_meta you should use the second action:

/**
 * @param int     $event_id The event ID (alias post ID).
 * @param array   $data     The saved meta fields. The new date should be somewhere in this array
 * @param WP_Post $event    The event itself (alias $post).
 */
function change_event_slug_on_save($event_id, $data, $event) {
    ...
}

add_action('tribe_events_update_meta', 'change_event_slug_on_save', 10, 3);