Laravel Middleware return variable to controller

I believe the correct way to do this (in Laravel 5.x) is to add your custom fields to the attributes property.

From the source code comments, we can see attributes is used for custom parameters:

 /**
 * Custom parameters.
 *
 * @var \Symfony\Component\HttpFoundation\ParameterBag
 *
 * @api
 */
public $attributes;

So you would implement this as follows;

$request->attributes->add(['myAttribute' => 'myValue']);

You can then retrieved the attribute by calling:

\Request::get('myAttribute');

Or from request object in laravel 5.5+

 $request->get('myAttribute');