根据产品类别有条件地操作WooCommerce购物车项目

Question

I'm in the process of creating a online food delivery website using WooCommerce and need to create a "Make it a Meal" type upsell for customers to purchase.

I've created a single product called "Make it a Meal" where users can select the drink and side of their choice (using variations). However what I need is for only one of these products to be able to be purchased per main meal.

Example:

• Product in "Main Meal" category is added to cart
• User can then add "Make it a Meal" product to cart
• User cannot add second "Make it a Meal" product unless they have a second product from the "Meal Meal" category i.e. only one per product
• If "Main Meal" product is removed from cart, then "Make it a Meal" is also removed.

Has anyone achieved this kind of functionality before? I've tried various plugins but currently had no luck.

Answer 1

Updated:

It's possible checking first on add-to-cart events (optionally displaying an error notice):

add_filter( 'woocommerce_add_to_cart_validation', 'checking_products_added_to_cart', 10, 3 );
function checking_products_added_to_cart( $passed, $product_id, $quantity) {

    $cat_add = 'Make it a Meal';
    $cat_src = 'Main Meal';

    if(has_term( $cat_add, 'product_cat', $product_id )):

        $main_meal_count = 0;
        $make_it_a_meal_count = 0;

        foreach (WC()->cart->get_cart() as $cart_item ){

            // Counting 'Main Meal' products in cart (with quantity)
            if( has_term( $cat_src, 'product_cat', $cart_item['product_id'] ))
                $main_meal_count += $cart_item['quantity'];

            // Counting 'Make it a Meal' products in cart (with quantity)
            if( has_term( $cat_add, 'product_cat', $cart_item['product_id'] ))
                $make_it_a_meal_count += $cart_item['quantity'];
        }

        if( $main_meal_count < ($make_it_a_meal_count + $quantity) ) {
            $passed = false;

            // Displaying a message (optionnal)
            wc_add_notice( 'my custom error message…', 'error' );
        }
    endif;

    return $passed;
}

Then you will need to check also when cart quantities are changed or cart items removed:

add_action( 'woocommerce_calculate_totals', 'check_removed_cart_items', 10, 1);
function check_removed_cart_items( $cart_object ) {

    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    $cat_add = 'Make it a Meal';
    $cat_src = 'Main Meal';

    $main_meal_count = 0;
    $make_it_a_meal_count = 0;

    // First loop: Counting cart items 'Main Meal' and 'Make it a Meal'
    foreach ($cart_object->get_cart() as $item_values ){

        // Counting 'Main Meal' products in cart (with quantity)
        if( has_term( $cat_src, 'product_cat', $item_values['product_id'] ))
            $main_meal_count += $item_values['quantity'];

        // Counting 'Make it a Meal' products in cart (with quantity)
        if( has_term( $cat_add, 'product_cat', $item_values['product_id'] )){
            $make_it_a_meal_count += $item_values['quantity'];
        }
    }

    $difference = intval($make_it_a_meal_count - $main_meal_count);

        echo '<p>$main_meal_count is '.$main_meal_count.'</p>';
        echo '<p>$make_it_a_meal_count is '.$make_it_a_meal_count.'</p>';
        echo '<p>$difference is '.$difference.'</p>';

    if( $main_meal_count < $make_it_a_meal_count ) {

        echo '<p>case1</p>';


        // Second Loop: Make necessary actions
        foreach ($cart_object->get_cart() as $cart_item_key => $cart_item ){

            // Targeting 'Make it a Meal'
            if( has_term( $cat_add, 'product_cat', $cart_item['product_id'] )){

                $item_qty = intval( $cart_item['quantity'] );

                if( $item_qty == 1 && $difference == 1 ){
                    $cart_object->remove_cart_item($cart_item_key);
                    break;
                } else {
                    if( $item_qty > 1 && $difference <= $item_qty ){
                        $cart_object->set_quantity( $cart_item_key, ($item_qty - $difference) );
                        break;
                    } else {
                        $cart_object->remove_cart_item($cart_item_key);
                    }
                }
            }
        }
    }
}

With that 2 hooked functions you have a complete solution.

Code goes in function.php file of your active child theme (or theme) or also in any plugin file.

This code is tested and works.