Request Rule is not catching the errors

namespace App\Http\Requests;
class ActionRequest extends Request
{
protected $dates = [
'timestamp',
'timestamp_end'
];
/**
 * Get the validation rules that apply to the request.
 *
 * @return array
 */
public function rules()
{
    $rules = [
        'timestamp' => 'required',
        'user_id' => 'required',
        'name' => 'required',
        'prm_action_type_id' => 'required'
    ];

    return $rules;
}

public function all($keys = null)
{

    $result = parent::all($keys);

    $types = app('\App\Repositories\System\Action\TypeRepository');

    $actionType = $types->find($result['prm_action_type_id']);

    if (!isset($actionType->appointment) && array_key_exists('timestamp_end', $result)) {
        unset($result['timestamp_end']);
    }

    return $result;
}

}

So i expected that if i have aRequest Class with rules and i override the all function the Request gets validated when i call ->all(). Instead i get undefined index prm_action_type_id (that is ok, cause i didnt even sent it to the server, but i expected to be catched by the Rules.)

I think i got here something wrong?