rest_send_allow_header

WordPress Version: 4.4

/**
 * Sends the "Allow" header to state all methods that can be sent to the current route.
 *
 * @since 4.4.0
 *
 * @param WP_REST_Response $response Current response being served.
 * @param WP_REST_Server   $server   ResponseHandler instance (usually WP_REST_Server).
 * @param WP_REST_Request  $request  The request that was used to make current response.
 * @return WP_REST_Response Response to be served, with "Allow" header if route has allowed methods.
 */
function rest_send_allow_header($response, $server, $request)
{
    $matched_route = $response->get_matched_route();
    if (!$matched_route) {
        return $response;
    }
    $routes = $server->get_routes();
    $allowed_methods = array();
    // Get the allowed methods across the routes.
    foreach ($routes[$matched_route] as $_handler) {
        foreach ($_handler['methods'] as $handler_method => $value) {
            if (!empty($_handler['permission_callback'])) {
                $permission = call_user_func($_handler['permission_callback'], $request);
                $allowed_methods[$handler_method] = true === $permission;
            } else {
                $allowed_methods[$handler_method] = true;
            }
        }
    }
    // Strip out all the methods that are not allowed (false values).
    $allowed_methods = array_filter($allowed_methods);
    if ($allowed_methods) {
        $response->header('Allow', implode(', ', array_map('strtoupper', array_keys($allowed_methods))));
    }
    return $response;
}