Manipulating WooCommerce cart items conditionally based on product categories

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.

LoicTheAztec LoicTheAztec · Accepted Answer · 2017-07-16T01:16:31

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.

Manipulating WooCommerce cart items conditionally based on product categories

1 Answers