Set new url from custom post field

Question

I've create a new custom post type "Event". I've added a custom field (Post Object) to the post type "Post" were you can select the corresponding Event.

So I create post new post and then I select Event X.

I want my URL to be domain.com/news/event-x/post-name.

I've create a function:

function custom_url_posts_event ($urlsub, $post) {
    if ($post->post_type == 'post') {
            
        //get event id
        $eventId = get_post_meta($post->ID, 'event_obj', true);
       
        //get venue slug
        $eventSlug = get_post_field( 'post_name', $eventId );
        
        $eventSlugSlash = '/'.$eventSlug;
        
        if (!empty($eventSlug)) {
            $point = strrchr(rtrim($urlsub, "/"), '/');
            $urlsub = str_replace($point, "/$eventSlug$point", $urlsub);
        }
    }
    return $urlsub;
}

add_filter('post_type_link', 'custom_url_posts_event', 11, 4);

When I output $urlsub I get the correct URL: domain.com/news/event-x/post-name So I guess that the filter above works correctly.

But the actual URL is still domain.com/news/post-name The URL isn't updated with the Event slug (event-x in this case).

I've also tried to change the permalink structure under Settings with: Custom struction: domain.com/news/%event_obj%/%postname%/

But %event_obj% is literally printed in the URL.

Answer 1

It sounds like the custom_url_posts_event function you've written is not being called by WordPress when generating the permalink for a post. This may be because the add_filter call is not properly hooked into WordPress or because the custom_url_posts_event function is not registered correctly with the post_type_link filter.

To fix this, you should first ensure that your add_filter call is properly hooked into WordPress. This can be done by ensuring that the add_filter call is placed inside a function hooked into the init action. Here is an example of how you can do this:

function wpdocs_custom_url_posts_event() {
    add_filter('post_type_link', 'custom_url_posts_event', 11, 4);
}
add_action( 'init', 'wpdocs_custom_url_posts_event' );

In this example, the wpdocs_custom_url_posts_event function is hooked into the init action, which means that it will be called when WordPress is initializing. Inside this function, the custom_url_posts_event function is registered with the post_type_link filter using the add_filter function.

You should also make sure that the custom_url_posts_event function is registered with the post_type_link filter using the correct number of arguments. In your code, the custom_url_posts_event function is defined with two arguments, but the add_filter call specifies that it should have four arguments. This is likely causing an error.

To fix this, you can update the custom_url_posts_event function to accept four arguments, like this:

function custom_url_posts_event($urlsub, $post, $leavename, $sample) {
    // your code here
}

Once you've made these changes, your custom_url_posts_event function should be called by WordPress when generating the permalink for a post, and you should be able to update the permalink with the slug of the corresponding event.