Custom bulk action for media gallery items

I had a very similar question (“How to make custom bulk actions work on the media/upload page?“) about Justin Stern’s Custom Bulk Action Demo, which was just answered.

My biggest piece of advice to you is to take the adaptation one step at a time: make sure you have export working for media before anything else. Don’t try to do two steps at once. (That’s the secret to all this computer stuff: break things into small, manageable pieces.)

For your specific questions at the end:

• Replacing check_admin_referer('bulk-posts') with check_admin_referer('bulk-media') will get rid of “Are you sure you want to do this?”.
• The hook add_action('load-upload.php', 'custom_bulk_action') may sound silly, but is fine.
• $sendback = admin_url( "upload.php" ) is fine.

In part 1, custom_bulk_admin_footer(), and part 3, custom_bulk_admin_notices(), you want to replace

• 'post' –> 'attachment'.

Elsewhere you need to replace

• post.php –> upload.php,
• edit –> upload, and
• post –> media.

Part 2, custom_bulk_action(), requires more-complicated adaptations. I recommend you use the code below (from the question linked above).

 add_action('load-upload.php', array(&$this, 'custom_bulk_action'));


function custom_bulk_action() {

//  ***if($post_type == 'attachment') {  REPLACE WITH:
    if ( !isset( $_REQUEST['detached'] ) ) {

    // get the action
    $wp_list_table = _get_list_table('WP_Media_List_Table');  
    $action = $wp_list_table->current_action();

    echo "\naction = $action\n</pre>";

    $allowed_actions = array("export");
    if(!in_array($action, $allowed_actions)) return;

    // security check
//  ***check_admin_referer('bulk-posts'); REPLACE WITH:
    check_admin_referer('bulk-media'); 

    // make sure ids are submitted.  depending on the resource type, this may be 'media' or 'ids'
    if(isset($_REQUEST['media'])) {
      $post_ids = array_map('intval', $_REQUEST['media']);
    }

    if(empty($post_ids)) return;

    // this is based on wp-admin/edit.php
    $sendback = remove_query_arg( array('exported', 'untrashed', 'deleted', 'ids'), wp_get_referer() );
    if ( ! $sendback )
      $sendback = admin_url( "upload.php?post_type=$post_type" );

    $pagenum = $wp_list_table->get_pagenum();
    $sendback = add_query_arg( 'paged', $pagenum, $sendback );

    switch($action) {
      case 'export':

        // if we set up user permissions/capabilities, the code might look like:
        //if ( !current_user_can($post_type_object->cap->export_post, $post_id) )
        //  wp_die( __('You are not allowed to export this post.') );

        $exported = 0;
        foreach( $post_ids as $post_id ) {

          if ( !$this->perform_export($post_id) )
            wp_die( __('Error exporting post.') );
          $exported++;
        }

        $sendback = add_query_arg( array('exported' => $exported, 'ids' => join(',', $post_ids) ), $sendback );
      break;

      default: return;
    }

    $sendback = remove_query_arg( array('action', 'action2', 'tags_input', 'post_author', 'comment_status', 'ping_status', '_status',  'post', 'bulk_edit', 'post_view'), $sendback );

    wp_redirect($sendback);
    exit();
  }
}