Changing file upload path for acf field using upload_prefilter inside Multisite

• xoxoxo

• December 22, 2021 at 12:30 am

Hi,

I run a Multisite Network with 4 sites in a sub domain config. I created a custom post type for videos.

I don’t want the video files to sit inside the wordpress folder structure, for various reasons, the main reasons being the size of my backups and the location being inside a custom CDN.

Now, what I have done works perfectly for the main site, because it uses /wp-content/uploads. So, when I upload a video into a video post, it saves that video file to /wp-content/uploads/videos, /wp-content/uploads/videos has been symlinked to my cdn – /mnt/cdn/videos (www-data has control). So the large video files goes into the cdn, away from the wordpress folder structure. All good.

https://main.site/wp-content/uploads/videos/911-trillions-follow-the-money-media.webm

But the sub sites, by default uses /wp-content/uploads/sites/x. If I use the same config for the sub sites, the video file is saved to the correct location, but wordpress then assigns an incorrect file url.

https://sub4.site/wp-content/uploads/sites/4//var/www/main/wp-content/uploads/videos/czechoslovakian-wolf-dog-media.webm

This is the function:

/** Set Video Upload Path ----------------------------------------------- **/

function video_upload_filter($errors, $file, $field) {
    
    add_filter('upload_dir', 'video_upload_dir');
    
}

add_filter('acf/upload_prefilter/key=field_6075238de0b09', 'video_upload_filter', 10, 3 );

function video_upload_dir($param) {
    
    if ((get_field('sys_site_slug', 'option') == 'main')) {
        $param['path'] = '/var/www/main.site/wp-content/uploads/videos';
        $param['url'] = 'https://main.site/wp-content/uploads/videos';
    }

    if ((get_field('sys_site_slug', 'option') == 'sub1')) {
        $param['path'] = '/var/www/main.site/wp-content/uploads/videos';
        $param['url'] = 'https://sub1/wp-content/uploads/videos';
    }

    if ((get_field('sys_site_slug', 'option') == 'sub2')) {
        $param['path'] = '/var/www/main.site/wp-content/uploads/videos';
        $param['url'] = 'https://sub2/wp-content/uploads/videos';
    }

    if ((get_field('sys_site_slug', 'option') == 'sub3')) {
        $param['path'] = '/var/www/main.site/wp-content/uploads/videos';
        $param['url'] = 'https://sub3/wp-content/uploads/sites/4/videos';
    }

    return $param;
}

I have tried many configurations, without success.

I am starting to think that the upload_prefilter is not doing it’s work when it comes to the sub sites like it does for the main site, when the upload_prefilter is called for the defined acf field.

This all sounds complicated, but if we just look at how upload_prefilter deals with multisite sub sites, we will know.

Help would be much appreciated.