Filter for custom trip if for tour extra.

Source

File: /inc/class-wp-travel-extras-frontend.php
Used by: /inc/class-wp-travel-extras-frontend.php

Parameter
$trip_id

Example:

function prefix_tour_extra_custom_trip_id( $trip_id ) {
    $trip_id = 20;
    return $trip_id;
}
add_filter( 'tour_extra_custom_trip_id', 'prefix_tour_extra_custom_trip_id' );