php - Cart discount for a product category based on quantity calculations

Question

I wan to add a function to woocommerce that will calculate a 10% discount when 12-23 items from one category is added to the cart.

Then if 24 - 47 items of the category are added it would be a 15% discount.

Last if 48+ items from this category are added it would be a 20% discount.

actual code example would be awesome as I am new to woocommerce

Answer 1

Updated — Corrected code mistakes and added enhancements in the outputted discount text

Here is the function hooked in woocommerce_cart_calculate_fees hook that is going to make the discount for that particular category (or subcategory too) based on cart item quantity calculations.

This is the code:

add_action( 'woocommerce_cart_calculate_fees', 'cart_items_quantity_wine_discount', 10, 1 );
function cart_items_quantity_wine_discount($cart_object) {

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

    // Set HERE your category (can be an ID, a slug or the name)
    $category = 34; // or a slug: $category = 'wine';

    $category_count = 0;
    $category_total = 0;
    $discount = 0;

    // Iterating through each cart item
    foreach($cart_object->get_cart() as $cart_item):

        if( has_term( $category, 'product_cat', $cart_item['product_id']) ):
            $category_count += $cart_item['quantity'];
            $category_total += $cart_item["line_total"]; // calculated total items amount (quantity x price)
        endif;

    endforeach;

    $discount_text = __( 'Quantity discount of ', 'woocommerce' );

    // ## CALCULATIONS ##
    if ( $category_count >= 12 && $category_count < 24 ) {
        $discount -= $category_total * 0.1; // Discount of 10% 
        $discount_text_output = $discount_text . '10%';
    } elseif ( $category_count >= 24 && $category_count < 48 ) {
        $discount -= $category_total * 0.15; // Discount of 15%
        $discount_text_output = $discount_text . '15%';
    } elseif ( $category_count >= 48 ) {
        $discount -= $category_total * 0.2; // Discount of 20%
        $discount_text_output = $discount_text . '20%';
    }

    // Adding the discount
    if ( $discount != 0 && $category_count >= 12 )
        $cart_object->add_fee( $discount_text_output, $discount, false );

    // Note: Last argument in add_fee() method is related to applying the tax or not to the discount (true or false)
}

Note: Last argument in add_fee() method is related to applying the tax or not to the discount…

Code is tested and fully functional.

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

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