yii2: trouble with using shopping cart extension

I trying to use https://github.com/omnilight/yii2-shopping-cart

I change my product model like this

class ShopItems extends ActiveRecord implements CartPositionInterface
{
    use CartPositionTrait;

    //...

    public function getPrice()
    {
        return $this->price;
    }

    public function getId()
    {
        return $this->id;
    }

    //...
}

I added action in my controller

public function actionAddToCart($id)
{
    $cart = new ShoppingCart();

    $model = ShopItems::findOne($id);
    if ($model) {
        $cart->put($model, 1);
        return $this->redirect(['cart-view']);
    }
    throw new NotFoundHttpException();
}

And of course add component in main config.

'components' => [
    'cart' => [
        'class' => 'yz\shoppingcart\ShoppingCart',
        'cartId' => 'my_application_cart',
    ]
]

How can i add product in cart now? I find this, but i can't understand how build action form.

Please, help!

UPD

I use action like this:

  public function actionAddToCart($id) {
    $cart = new ShoppingCart();
    $model = ShopItems::findOne($id);
    if ($model) {
      $cart->put($model, 1);
      return print_r($cart);
//      return $this->redirect(['cart-view']);
    }
    throw new NotFoundHttpException();
  }

And get next:

And after it <?php print_r( Yii::$app->cart ) ?> in cart-view show this:

yz\shoppingcart\ShoppingCart Object ( [storeInSession] => 1 [session] => yii\web\Session Object ( [flashParam] => __flash [handler] => [_cookieParams:yii\web\Session:private] => Array ( [httponly] => 1 ) [_hasSessionId:yii\web\Session:private] => [_events:yii\base\Component:private] => Array ( ) [_behaviors:yii\base\Component:private] => ) [cartId] => my_application_cart [_positions:protected] => Array ( ) [_events:yii\base\Component:private] => Array ( ) [_behaviors:yii\base\Component:private] => )

Solution

In your product view:

<?php $form = ActiveForm::begin(['class'=>'form-horizontal', 'action'=>Url::toRoute(['controllername/add-to-cart','id'=>$product->id])]); ?>

    <?=Html::input('submit','submit','Add to cart',[
                'class'=>'button add',

              ])?>
<?php ActiveForm::end(); ?>

And in your controller:

public function actionAddToCart($id)
{
    $cart = Yii::$app->cart;;

    $model = ShopItems::findOne($id);
    if ($model) {
        $cart->put($model, 1);
        return $this->redirect(['cart-view']);
    }
    throw new NotFoundHttpException();
}

Cart index view:

<?php

        /** @var ShoppingCart $sc */
        foreach(Yii::$app->cart->positions as $position){
          echo $this->render('_cart_item',['position'=>$position]);
          //var_dump($position);
        }


      ?>

in _cart_item view $position is ShopItems model:

<?= $position->id ?>
<?= $position->price ?>
<?= $position->name ?>
<?= $position->quantity ?>