Symfony: Service in other Service not loaded (Too few arguments)

Background

I have a OptionHelper-Class that is looking in the database-table, where I store some flexible parameters. This class is working fine in Controllers.

Now I want to use this class in a function of another Service, but it explodes with the below mentioned error message.

OptionHelper.php

namespace AppService;


use AppEntityOptions;
use DoctrineORMEntityManagerInterface;

class OptionHelper {
    private $emi;

    public function __construct(EntityManagerInterface $emi) {
        $this->emi = $emi;
    }

    public function get(string $optionName) {
        $repository = $this->emi->getRepository(Options::class);
        $options    = $repository->findOneBy([ 'optionname' => $optionName ]);
        $value      = $options->getOptionvalue();

        return $value;
    }
}

CartItem.php

namespace AppService

class CartItem {
    [...]
    public function __construct($name, $number, $id) {
        $this->name   = $name;
        $this->number = $number;
        $this->id     = $id;
    }
    [...]
    private function getPrice(OptionHelper $optionHelper) { //<-- ERROR in this line
        $price = $optionHelper->get('price');    
        return $price;
    }
}

Controller

   [...]
   public function addItem($name, $number, $id) {
      $cartItem = new CartItem($name, $number, $id);
   }

Error-Msg

Too few arguments to function AppServiceCartItem::getPrice(), 0 passed in /src/Service/CartItem.php on line 89 and exactly 1 expected

Question

Why isn’t it working in another Service? I tried also to put it into the constructor of CartItem-Class, but doesn’t work too.

Do I have to add something in services.yaml? But I have no idea, how to do it.

Thanks in advance for any help!

Answer

After a while I found the problem. It seems that you should never do this, because it disables the autowiring functionality.

• use new ClassName($x, $y) to create a new instance
• only use autowirable Services in the constructor of a class

wrong

    public function __construct($name, $number, $id) {
        $this->name   = $name;
        $this->number = $number;
        $this->id     = $id;
    }

   public function addItem($name, $number, $id) {
      $cartItem = new CartItem($name, $number, $id);
   }

correct

    public function __construct(OnlyServices $onlyServices) {
       [...]
    }

    public function create($name, $number, $id) {
        $this->name   = $name;
        $this->number = $number;
        $this->id     = $id;
    }

   public function addItem($name, $number, $id, CartItem $cartItem) {
      $cartItem->create($name, $number, $id);
   }