Filter to intercept cached static HTML files, right before they are serverd.

I tried this filter, I am almost sure this is the one, but it doesn’t log anything.

add_filter('wp_cache_served_cache_file', 'modify_served_cache_file', 10, 1);

function modify_served_cache_file($cache_file) {
    // Inspect the cache file being served
    error_log("Serving cache file: " . $cache_file);

    // Modify the cache file path or manipulate its content if needed
    // Example: Read and replace content dynamically
    if (file_exists($cache_file)) {
        $cache_data = file_get_contents($cache_file);

        // Example: Replace the domain dynamically based on the request
        $current_domain = $_SERVER['HTTP_HOST'];
        $cached_domain = 'primary-domain.com'; // Replace with your cache domain

        // Replace domain in cached data
        $cache_data = str_replace($cached_domain, $current_domain, $cache_data);

        // Save the modified content back to the file (optional)
        file_put_contents($cache_file, $cache_data);
    }

    // Return the modified or original cache file path
    return $cache_file;
}

This is my WP_DEBUG Setup

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false ); // Prevents errors from displaying on the frontend
@ini_set( 'log_errors', 1 );
@ini_set( 'display_errors', 0 ); // Prevents errors from displaying on the frontend

WP Super Cache is set to operate in Simple Mode.

Any ideas would help ??

Hi there, @wowlayers,

Thanks for explaining your issue and sharing your script attempt to achieve what you requested ??

This goes a bit beyond my technical skills, so I have asked our developers to take a look at your request to advise you accordingly. We’ll get back to you as soon as we heard from them!

Hello there @wowlayers!

Thank you for the code example and information about your setup.

I think you’re on the right track and you’re using the right filter! Is it possible that you’re adding it to your theme?

If so that wouldn’t work, because if WordPress serves a cached file, it stops executing code that would normally execute on a non-cached request. In this case, any PHP code you add to the theme (or the theme’s PHP code) wouldn’t get executed.

Thankfully, WP Super Cache allows for a workaround.

First, you’ll need to modify your snippet a bit. Change this line:

add_filter('wp_cache_served_cache_file', 'modify_served_cache_file', 10, 1);

to this:

add_cacheaction('wp_cache_served_cache_file', 'modify_served_cache_file' );

This will tell WP Super Cache to run your code.

After that, create a new .php file inside wp-content/plugins/wp-super-cache/plugins/, and add the updated code to it.

This will allow WordPress to execute your code and do the replacements!

Fingers crossed this works.

If it doesn’t, leave a comment so we can continue investigating.

Cheers!

• This reply was modified 1 month, 3 weeks ago by Pete (a11n). Reason: clarify file creation

@dilirity thanks for taking the time to write.

In the end it seems WP Super Cache, creates separate folders for each domain, so my issue is resolved ??

Hey @wowlayers,

We’re glad to hear that your issue got eventually solved and you seem to be all set now ??

I’m going to mark this thread as solved. If you have any further questions or need more help, you’re welcome to open another thread here. Cheers!