Argument 1 passed to yii2mod\cart\Cart::add() must be an instance of yii2mod\cart\models\CartItemInterface

[gabriele-carbonai]

Hello,
I have this error:
Argument 1 passed to yii2mod\cart\Cart::add() must be an instance of yii2mod\cart\models\CartItemInterface

is in this method:
public function add(CartItemInterface $element, $save = true): self

I follow the doc and configured the extension in correct way:

'cart' => [
            'class' => 'yii2mod\cart\Cart',
            // you can change default storage class as following:
            'storageClass' => [
                'class' => 'yii2mod\cart\storage\DatabaseStorage',
                // you can also override some properties
                'deleteIfEmpty' => true
            ]
        ],

Then in my controller, just this simple code:

public function actionCart()
{
        $cart = \Yii::$app->cart;
        $cart->add(2); 
}

I tried to:

1. Remove configuration in main.php and is not working because configuration are missing, so mean is correctly configurate
2. implement CartItemInterface in controller
3. implement add() method in model and call from controller
4. I try to pass in method integer, array and string

Where I am wrong?
Thank you

[ihorchepurnyi]

Hi, you need to implement CartItemInterface in your model.

[ihorchepurnyi]

From docs

// Product is an AR model implementing CartProductInterface
$product = Product::findOne(1);

// add an item to the cart
$cart->add($product);

[gabriele-carbonai]

In this case I can not add serialize post?

[ihorchepurnyi]

You can only add active record model to cart.

[gabriele-carbonai]

ok understand, thank you

[mavelar]

the solution?