WooCommerce: display products discounted price in cart table

functions.php

<?php
/*
 * Display discounted products prices in the cart table.
 *
 * Modification of code provided here https://businessbloomer.com/woocommerce-display-cart-item-subtotal-coupon-discount/.
 */
add_filter( 'woocommerce_cart_item_subtotal', 'if_coupon_slash_item_subtotal', 99, 3 );
add_filter( 'woocommerce_cart_item_price', 'if_coupon_slash_item_subtotal', 99, 3 );

/**
 * Display months discounted prices on cart page table.
 *
 */
function if_coupon_slash_item_subtotal( $subtotal, $cart_item, $cart_item_key ) {

	global $woocommerce;

	// Check if cart has coupon.
	if ( ! $woocommerce->cart->has_discount() ) {
		return $subtotal;
	}

	// Get coupons.
	$coupons = WC()->cart->get_applied_coupons();

	// Loop through coupons.
	foreach ( $coupons as $coupon ) {

		// Create coupon object.
		$coupon = new WC_Coupon( $coupon );

		// Check if specific coupon is applied.
		if ( $woocommerce->cart->has_discount( $coupon->get_code() ) ) {

			// Check if products in cart are from a specific category).
			if ( has_term( 'my-category-slug', 'product_cat', $cart_item['product_id'] ) ) {

				// If coupon type is fixed_product.
				if ( 'fixed_product' === $coupon->get_discount_type() ) {
					$newsubtotal = wc_price( $cart_item['data']->get_price() - $coupon->get_amount() * $cart_item['quantity'] );
				} else { // If coupon type is percentage.
					$newsubtotal = wc_price( $cart_item['data']->get_price() * ( 1 - ( '0.' . $coupon->get_amount() ) ) * $cart_item['quantity'] );
				}

				$subtotal = sprintf( '<s>%s</s> %s', $subtotal, $newsubtotal );
			}
		}
	}

	return $subtotal;
}

Thanks man,
on line: 36, we can use if ( has_term( $coupon->product_categories, 'product_cat', $cart_item['product_id'] ) ) {

to automatically change subtotal on applied product categories

Nice trick! Works for me

Here's an updated function based on the above with a few extra checks, including product ID inclusions and exclusions as well as product cat inclusions and exclusions. It also checks if the calling filter is the subtotal one for applying the quantity multiplier in the equations at the end.

function if_coupon_slash_item_subtotal($subtotal, $cart_item, $cart_item_key){
	// Check if cart has coupon.
	if (!WC()->cart->has_discount()){
		return $subtotal;
	}

	// Get coupons.
	$coupons = WC()->cart->get_applied_coupons();

	// Loop through coupons.
	foreach ($coupons as $coupon){
		// Create coupon object.
		$coupon = new WC_Coupon($coupon);

		// Check if products are not resticted from this coupon
		$included_products = true;
		$included_cats = true;

		if (count($product_ids = $coupon->get_product_ids()) > 0){
			if (!in_array($cart_item['product_id'], $product_ids, false)){
				$included_products = false;
			}
		}
		if (count($exluded_product_ids = $coupon->get_excluded_product_ids()) > 0){
			if (in_array($cart_item['product_id'], $exluded_product_ids, false)){
				$included_products = false;
			}
		}

		if (count($product_cats = $coupon->get_product_categories()) > 0){
			if (!has_term($product_cats, 'product_cat', $cart_item['product_id'])){
				$included_cats = false;
			}
		}
		if (count($excluded_product_cats = $coupon->get_excluded_product_categories()) > 0){
			if (has_term($excluded_product_cats, 'product_cat', $cart_item['product_id'])){
				$included_cats = false;
			}
		}

		if ($included_products && $included_cats){
			$filter = current_filter();

			// If coupon type is fixed_product.
			if ($coupon->get_discount_type() === "fixed_product"){
				$newsubtotal = wc_price(($cart_item['data']->get_price() - $coupon->get_amount()) * (int)($filter === 'woocommerce_cart_item_subtotal' ? $cart_item['quantity'] : 1));
			} else{ // If coupon type is percentage.
				$newsubtotal = wc_price($cart_item['data']->get_price() * (float)(1 - ('0.' . $coupon->get_amount())) * (int)($filter === 'woocommerce_cart_item_subtotal' ? $cart_item['quantity'] : 1));
			}
		}
	}

	return $subtotal;
}
add_filter('woocommerce_cart_item_subtotal', 'if_coupon_slash_item_subtotal', PHP_INT_MAX, 3);
add_filter('woocommerce_cart_item_price', 'if_coupon_slash_item_subtotal', PHP_INT_MAX, 3);