Inheritance: extends Illuminate\Foundation\Http\FormRequest
 public function postUser(CheckoutUserRequest $request)
 {
     $orderData = Session::get('order_data');
     $request->merge(['password' => bcrypt($request->get('password'))]);
     $user = User::create($request->all());
     Auth::guard('web')->login($user);
     $orderData['user_id'] = $user->id;
     Session::put('order_data', $orderData);
     return redirect()->route('checkout.step.shipping-address');
 }