my $response = $ua->post(
        $conf{base_url}.'/ws.php?format=json',
        {
            method => 'pwg.categories.getImages',
            cat_id => $params{album_id},
            per_page => 1000000,
        }
    );

    foreach my $image_href (@{from_json($response->content)->{result}{images}}) {
        $photos_of_album{ $params{album_id} }{ $image_href->{file} } = $image_href->{id};
    }