Set cart item product generated sale price only for specific products in Woocommerce

Question

Following Set only specific products sale price programmatically in WooCommerce 3, the related cart items price are not updated with the product\'s generated sale price.

Answer 1

To get the right generated sale price in cart item for specific product IDs try the following:

// HERE below in the array set your specific product IDs
function specific_product_ids(){
    return array(37, 41); //  <===  <===  <===  <===  Your Product IDs
}

// Generating dynamically the product "regular price"
add_filter( 'woocommerce_product_get_regular_price', 'custom_dynamic_regular_price', 10, 2 );
add_filter( 'woocommerce_product_variation_get_regular_price', 'custom_dynamic_regular_price', 10, 2 );
function custom_dynamic_regular_price( $regular_price, $product ) {
    if( ( empty($regular_price) || $regular_price == 0 ) && in_array($product->get_id(), specific_product_ids() ) )
        return $product->get_price();
    else
        return $regular_price;
}


// Generating dynamically the product "sale price"
add_filter( 'woocommerce_product_get_sale_price', 'custom_dynamic_sale_price', 10, 2 );
add_filter( 'woocommerce_product_variation_get_sale_price', 'custom_dynamic_sale_price', 10, 2 );
function custom_dynamic_sale_price( $sale_price, $product ) {
    $rate = 0.8;
    if( ( empty($regular_price) || $regular_price == 0 ) && in_array($product->get_id(), specific_product_ids() ) )
        return $product->get_regular_price() * $rate;
    else
        return $sale_price;
};

// Displayed formatted regular price + sale price
add_filter( 'woocommerce_get_price_html', 'custom_dynamic_sale_price_html', 20, 2 );
function custom_dynamic_sale_price_html( $price_html, $product ) {
    if( $product->is_type('variable') ) return $price_html;

    if( in_array($product->get_id(), specific_product_ids() ) ) {
        $price_html = wc_format_sale_price( wc_get_price_to_display( $product, array( 'price' => $product->get_regular_price() ) ), wc_get_price_to_display(  $product, array( 'price' => $product->get_sale_price() ) ) ) . $product->get_price_suffix();
    }
    return $price_html;
}

// Set cart item generated "sale price" for specific product IDs
add_action( 'woocommerce_before_calculate_totals', 'set_cart_item_sale_price', 10, 1 );
function set_cart_item_sale_price( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    // Iterate through each cart item
    foreach( $cart->get_cart() as $cart_item ) {
        if( in_array($cart_item['data']->get_id(), specific_product_ids() ) ) {
            $price = $cart_item['data']->get_sale_price(); // get sale price
            $cart_item['data']->set_price( $price ); // Set the sale price
        }
    }
}

Code goes in function.php file of your active child theme (active theme). Tested and works.