How to have multiple rewrite endpoints in the same URL?

Question

I'd like to add multiple query_var / value pairs to any URL. For example the base URL of a page is:

example.com/nice-page/

I can already achieve one endpoint like (for example, an on-page subgallery):

example.com/nice-page/my-gallery/animals/cats

Where my-gallery is the query_var and animals/cats is its value. Using this:

add_rewrite_endpoint('my-gallery', EP_PAGES);
add_rewrite_endpoint('my-lightbox', EP_PAGES);

I also need this to work:

example.com/nice-page/my-gallery/animals/cats/my-lightbox/1234

Where I'd like to register my-lightbox as an additional endpoint or query_var, because it could be used independently from without my-gallery, such as:

example.com/another-page/my-lightbox/2345

Currently I get the entire animals/cats/my-lightbox/1234 as the value. I can't make WP aware that a new query_var starts at my-lightbox when my-gallery is alrady present. It seems that rewrite tags are acting on the entirety of the input URL, and endpoints are acting on the end of the input URL, but the regex $ end-anchor is always there. Is it even possible to use the rewrite api to prettify multiple query_vars into a complex URL?

Answer 1

I also need this to work:

example.com/nice-page/my-gallery/animals/cats/my-lightbox/1234

Where I'd like to register my-lightbox as an additional endpoint or query_var, because it could be used independently from without my-gallery, such as:

example.com/another-page/my-lightbox/2345

Here's an example of doing it using add_rewrite_rule():

add_action( 'init', function() {
    // This will let you use get_query_var( 'my-gallery' ).
    add_rewrite_endpoint( 'my-gallery', EP_PAGES );

    // This will let you use get_query_var( 'my-lightbox' ).
    add_rewrite_endpoint( 'my-lightbox', EP_PAGES );

    add_rewrite_rule(
        '(.?.+?)/(?:my-gallery/(.+?)/my-lightbox/(\d+)|my-gallery/(.+?)|/?my-lightbox/(\d+))/?$',
        'index.php?pagename=$matches[1]&my-gallery=$matches[2]&my-lightbox=$matches[3]',
        'top'
    );

    // This is just for testing purposes. You should instead go to the Permalink
    // Settings page and click on the Save Changes button to flush the rules. =)
    //flush_rewrite_rules();
} );

[EDIT] Alternate version without using add_rewrite_endpoint():

add_filter( 'query_vars', function( $qv ) {
    // This will let you use get_query_var( 'my-gallery' ).
    $qv[] = 'my-gallery';

    // This will let you use get_query_var( 'my-lightbox' ).
    $qv[] = 'my-lightbox';

    return $qv;
} );

add_action( 'init', function() {
    add_rewrite_rule(
        '(.?.+?)/(?:my-gallery/(.+?)/my-lightbox/(\d+)|my-gallery/(.+?)|/?my-lightbox/(\d+))/?$',
        'index.php?pagename=$matches[1]&my-gallery=$matches[2]&my-lightbox=$matches[3]',
        'top'
    );
} );

And I have tested it on these URLs:

• example.com/nice-page/my-gallery/animals/cats/my-lightbox/1234
• example.com/nice-page/my-gallery/animals/cats
• example.com/nice-page/my-lightbox/1234

..where get_query_var( 'my-gallery' ) returns animals/cats (for the first and second URLs) and get_query_var( 'my-lightbox' ) returns 1234 (for the first and third URLs).