Set programmatically product sale price and cart item prices in Woocommerce 3

Question

This is the continuation of : Set product sale price programmatically in WooCommerce 3

The answer works, however once a user adds the product to cart, the old price stil

Answer 1

Hope this code is helpful for you

add_filter( 'woocommerce_get_price_html', 'bbloomer_alter_price_display', 9999, 2 );

function bbloomer_alter_price_display( $price_html, $product ) {

  // ONLY ON FRONTEND
  if ( is_admin() ) return $price_html;

  // ONLY IF PRICE NOT NULL
  if ( '' === $product->get_price() ) return $price_html;

  // IF CUSTOMER LOGGED IN, APPLY 20% DISCOUNT   
  if ( wc_current_user_has_role( 'customer' ) ) {
    $orig_price = wc_get_price_to_display( $product );
    $price_html = wc_price( $orig_price * 0.80 );
  }
  return $price_html;
}

add_action( 'woocommerce_before_calculate_totals', 'bbloomer_alter_price_cart', 9999 );

function bbloomer_alter_price_cart( $cart ) {

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

  if ( did_action( 'woocommerce_before_calculate_totals' ) >= 2 ) return;

  // IF CUSTOMER NOT LOGGED IN, DONT APPLY DISCOUNT
  if ( ! wc_current_user_has_role( 'customer' ) ) return;

  // LOOP THROUGH CART ITEMS & APPLY 20% DISCOUNT
  foreach ( $cart->get_cart() as $cart_item_key => $cart_item ) {
    $product = $cart_item['data'];
    $price = $product->get_price();
    $cart_item['data']->set_price( $price * 0.80 );
  }
}