function wp_modify_uploaded_file_names($image_name) {
// Get the parent post ID, if there is one
if( isset($_GET['post_id']) ) {
$post_id = $_GET['post_id'];
} elseif( isset($_POST['post_id']) ) {
$post_id = $_POST['post_id'];
}
// Only do this if we got the post ID--otherwise they're probably in
// the media section rather than uploading an image from a post.
if(is_numeric($post_id)) {
// Get the post slug
$post_obj = get_post($post_id);
$post_slug = $post_obj->post_name;
// If we found a slug
if($post_slug) {
$random_number = rand(100,999999);
$image_name['name'] = $post_slug . '-' . $random_number . '.jpg';
}
}
return $image_name;
}
add_filter('wp_handle_upload_prefilter', 'wp_modify_uploaded_file_names', 1, 1);