CUNY Academic Commons

Ugh, good catch.

The problem is the customizer functionality of WordPress saves the absolute URL of the theme assets from the current URL. Because the original customizer changes were made on the mapped domain, those theme asset URLs are now using the mapped domain instead of the subdomain.

The following snippet fixes this for the various customizer options requiring attachments:

function cac_set_mapped_url_to_subdomain( $url ) {
    global $wpdb;

    // bail if we're on a mapped domain
    if ( cac_is_domain_mapping_enabled_for_current_blog() ) {
        return $url;
    }

    // Check if the currnet blog has a mapped domain...
    $domain = $wpdb->get_var( "SELECT domain FROM {$wpdb->dmtable} WHERE blog_id = '{$wpdb->blogid}' AND active = 1 LIMIT 1" );
    if ( empty( $domain ) ) {
        return $url;
    }

    $url = str_replace( '://' . $domain, '://' . $GLOBALS['current_blog']->domain, $url );
    $url = set_url_scheme( $url, is_ssl() ? 'https' : 'http' );

    return $url;
}
add_filter( 'theme_mod_header_image', 'cac_set_mapped_url_to_subdomain' );
add_filter( 'theme_mod_header_video', 'cac_set_mapped_url_to_subdomain' );
add_filter( 'theme_mod_background_image', 'cac_set_mapped_url_to_subdomain' );
add_filter( 'theme_mod_custom_logo', 'cac_set_mapped_url_to_subdomain' );

But, it uses an uncached DB query because the WPMU Domain Mapping plugin does not cache this info from their DB table.

Since there are way more non-mapped domains, do we want to write a caching layer for WPMU Domain Mapping so we can then apply this snippet?

Yeah, I'd say it's worth it to write that layer. It'd benefit us elsewhere. Thanks!

Boone Gorges wrote:

Yeah, I'd say it's worth it to write that layer. It'd benefit us elsewhere. Thanks!

I've written an object cache layer for wordpress-mu-domain-mapping in a separate branch for our cac repo:
https://github.com/cuny-academic-commons/cac/compare/1.13.x...dm-object-cache

Let me know what you think.

This looks good to me, Ray. A couple non-critical questions:

- Do you think there's a reason why the plugin authors haven't added caching for this in the past? It seems an obvious win. Maybe there's problems in multi-server environments or something? Would it make sense to package this as a PR/patch for the plugin?
- Is there benefit (maybe not direct to this ticket, but in general) to adding caching in the other direction as well? Ie blog ID lookup given a domain - the query that takes place in sunrise.php. (I think the cache system is booted by this point?)

I'd say you're good to update https://redmine.gc.cuny.edu/issues/9735#note-2 in light of the new cached function, and add it to the codebase for 1.13.2.

Would it make sense to package this as a PR/patch for the plugin?

I couldn't find a Git repo for the wordpress-mu-domain-mapping plugin anywhere. There are some forks on Github though. Could post the patch on the wp.org support forums and hope for the best.

Ie blog ID lookup given a domain - the query that takes place in sunrise.php. (I think the cache system is booted by this point?)

Good spot about sunrise.php. I can look into adding caching by domain later down the road, but as you mention, it's not critical for this ticket. We would also have to move some other code into sunrise.php like the wp_cache_add_global_groups( 'wpmu_dm' ); call.

For now, I'll merge what I have into 1.13.x branch and add the code I wrote to address this specific ticket.

Thanks for the feedback!

Thanks! Going to mark resolved in advance of the release.