How can I add an Author filter to the Media Library?

Question

By default the WordPress Media Library allows you to filter results by their type or date. How can I add a third drop down to list and filter by author?

Currently we have this:

I'd like to have the following:

According to this ticket (unless I'm reading it wrong) the code was added three years ago to /wp-admin/includes/class-wp-media-list-table.php to allow this, but I don't see how this actually works.

The codex also says that it's possible to modify the media library modal window you get when editing a page or post with:

add_filter( 'ajax_query_attachments_args', 'show_current_user_attachments', 10, 1 );
function show_current_user_attachments( $query = array() ) {
    $user_id = get_current_user_id();
    if( $user_id ) {
        $query['author'] = $user_id;
    }
    return $query;
}

So I'd think that it's possible to do something similar on the main Media Library page, but I can't see how.

Answer 1

In your question you showed the image which is grid-view and that codex belongs to list-view. So I am confused here for which section you are talking about.

Grid View : not possible unless you change the core as they don't provide any hook and the whole media section was created by jquery, backbone and unserscore. Please look into media-grid.min.js or media-grid.js for code.

List View : in this view you can easily add dropdown. here is the script to do this. If you want then add parse_query or pre_get_posts filter to change the query for the dropdown. As I am setting author to url, wordpress itself sets it for me so need for those filters.

function media_add_author_dropdown()
{
    $scr = get_current_screen();
    if ( $scr->base !== 'upload' ) return;

    $author   = filter_input(INPUT_GET, 'author', FILTER_SANITIZE_STRING );
    $selected = (int)$author > 0 ? $author : '-1';
    $args = array(
        'show_option_none'   => 'All Authors',
        'name'               => 'author',
        'selected'           => $selected
    );
    wp_dropdown_users( $args );
}
add_action('restrict_manage_posts', 'media_add_author_dropdown');

Here are the references

1. restrict_manage_posts
2. pre_get_posts
3. parse_query

Edit #1: Added author filter after this comment

function author_filter($query) {
    if ( is_admin() && $query->is_main_query() ) {
        if (isset($_GET['author']) && $_GET['author'] == -1) {
            $query->set('author', '');
        }
    }
}
add_action('pre_get_posts','author_filter');

Answer 2

If you need this for your own site then instead of code you can go to list view and click on author name under Author column. That would give you the list of media for that particular author. See below screenshot.

But if you are doing this for any client then you will need a code to provide user friendly way :) like the dropdown you shown in your screenshot :)