You need to introduce an if
statement for checking product id, in above code:
add_action( 'woocommerce_before_calculate_totals', 'add_custom_price' );
function add_custom_price( $cart_object ) {
$custom_price = 10; // This will be your custome price
$target_product_id = 598;
foreach ( $cart_object->cart_contents as $value ) {
if ( $value['product_id'] == $target_product_id ) {
$value['data']->price = $custom_price;
}
/*
// If your target product is a variation
if ( $value['variation_id'] == $target_product_id ) {
$value['data']->price = $custom_price;
}
*/
}
}
Add this code anywhere and make sure that this code is always executable.
After adding this code, when you'll call:
global $woocommerce;
$woocommerce->cart->add_to_cart(598);
Only this product will be added with overridden price, other products added to cart will be ignored for overriding prices.
Hope this will be helpful.