Request is ajax - SOLVED

I remember there was a method $request->isAjax()
not longer defined

How can I get if a request is ajax in middleware?

Just add this method (into your middleware) to detect Ajax requests:

use Psr\Http\Message\RequestInterface;

// ...

/**
 * Check whether a request is Ajax or not.
 *
 * @param RequestInterface $request The request
 *
 * @return bool The status
 */
private function isAjax(RequestInterface $request)
{
    return strtolower($request->getHeaderLine('X-Requested-With')) === 'xmlhttprequest';
}