WordPress: Use user ids as subfolders for uploaded media files

functions.php

<?php

add_filter( 'upload_dir', 'themeslug_upload_dir' );

/**
 * Use user ids as subfolders for uploaded media files.
 */
function themeslug_upload_dir( $uploads ) {
  $user_id = get_current_user_id() ?: 'anonymous';

  $subdir = "/users/${user_id}" . $uploads['subdir'];

  $uploads['path'] = $uploads['basedir'] . $subdir;
  $uploads['url'] = $uploads['baseurl'] . $subdir;

  return $uploads;
}

Japanese post:

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