Woocommerce购物车中仅允许两种产品中的一种

Question

I have two grouped products A and B :

1) Product A

• Woocommerce subscription functionality Alpha ( monthly subscription)
• Woocommerce subscription platform (annual subscription)

2) Product B

• Woocommerce subscription functionality Alpha ( annual subscription)
• Woocommerce subscription platform (annual subscription)

The difference is in the subscription Alfa.

Problem

I want that "Alpha" appears only once in the cart (monthly or annual).

Current status

If a user adds to the cart "A" (it has an alpha monthly + platform per year). Then, if it changes his mind and clicks on "B", the system will tell him that the platform cannot be added once again, but alpha annually is added - that means that alpha is in the cart twice, which is not ok.

There is also one X product - separate "x subscription", which can be ordered (not a group product).

One solution that I see is that prior to adding to the basket, the system should first empty the basket.

A possible solution is also to check if a specific product is already in the cart (eg alpha - monthly) and remove it and add a new one (the one that is passed when the user clicked on add to cart).

I found one code on the web (that goes into functions.php). Function empties the cart but empties it for every added product. So, in the cart, then only "platform" is left (because the system probably empties the cart, adds the alpha, then empties the cart again and then adds the platform).

Here is the code:

add_filter( 'woocommerce_add_cart_item_data', 'wdm_empty_cart', 10,  3);

function wdm_empty_cart( $cart_item_data, $product_id, $variation_id ) 
{
    global $woocommerce;
    $woocommerce->cart->empty_cart();

    // Do nothing with the data and return
    return $cart_item_data;
}

How to allow only one from that 2 specific products to be in cart?

Answer 1

The code below is based on your 2 "Alpha" subscriptions product IDs. It will remove the first product added to cart if both products are in cart. You will have to set in this function both products IDs:

add_action('woocommerce_before_calculate_totals', 'checking_and_removing_cart_items', 20, 1 );
function checking_and_removing_cart_items( $cart ){
    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    if ( did_action( 'woocommerce_before_calculate_totals' ) >= 2 )
        return;

    // HERE below define your "Alpha" products
    $alpha_monthly_id = 37;
    $alpha_yearly_id = 53;
    $found_monthly = $found_yearly = false;
    $keys = array();

    // Checking cart items
    foreach( $cart->get_cart() as $key => $cart_item ) {
        if( $cart_item['product_id'] == $alpha_monthly_id ){
            $found_monthly = true;
            $keys[] = $key;
        } elseif( $cart_item['product_id'] == $alpha_yearly_id ){
            $found_yearly = true;
            $keys[] = $key;
        }
    }
    // If both product found, we remove the first one
    if( $found_monthly && $found_yearly ){
        $cart->remove_cart_item($keys[0]);

        // (optional) Remove notices before they get displayed
        if( ! is_checkout() )
            wc_clear_notices(); 
    }
}

Code goes in function.php file of the active child theme (or active theme).

Tested and works