Symfony2正在构建购物车。 增加，减少数量

Question

I have a few problems regarding the quantities when you want to add more than one of the same products to your shopping cart.

The problem is that when I increase the quantity by one for some reason it increases it by 2. For example I add one products, so the quantity is 1. I add the same product again and the quantity becomes 3 instead of 2.

  if( isset($cart[$id]) ) {

            $qtyAvailable = $product->getStock();

                if( $qtyAvailable >= $cart[$id] = $cart[$id] + 1 ) {
                $cart[$id] = $cart[$id] + 1;; 
            } else {

                return $this->redirect($this->generateUrl('cart'));
            }

Looks liek a simple code but why does it do that?

Answer 1

Your if part is increasing your quantity and inside if you are again adding 1 in quantity

if( $qtyAvailable >= $cart[$id] = $cart[$id] + 1 ) {
                         here ^^^^^^^^  

Try this criteria

if ( $qtyAvailable > $cart[ $id ]) {
    $cart[ $id ] = $cart[ $id ] + 1;;
} else {
    return $this->redirect( $this->generateUrl( 'cart' ) );
}