updateCartDiscountCodes method

Future<Cart> updateCartDiscountCodes({ required String cartId, required List<String> discountCodes, bool reverse = false, bool includeWarnings = false, })

update cart discount codes

If the reverse is set to true, the line items in the cart will be in reverse order.

Implementation

Future<Cart> updateCartDiscountCodes({
  required String cartId,
  required List<String> discountCodes,
  bool reverse = false,
  bool includeWarnings = false,
}) async {
  final MutationOptions updateDiscountCodes = MutationOptions(
    document: gql(updateCartDiscountCodesMutation(includeWarnings: includeWarnings)),
    variables: {
      'cartId': cartId,
      'discountCodes': discountCodes,
      'country': ShopifyLocalization.countryCode,
      'reverse': reverse
    },
  );
  QueryResult result = await _graphQLClient!.mutate(updateDiscountCodes);
  checkForError(result,
      key: 'cartDiscountCodesUpdate', errorKey: 'userErrors');

  final Map payload = result.data?['cartDiscountCodesUpdate'] ?? const {};
  final Cart cart = Cart.fromJson(payload['cart'] ?? const {});
  if (!includeWarnings) return cart;

  // `warnings` (CartWarningCode + localized message) are payload-level, not linked to a specific
  // code, so pair them positionally with the non-applicable codes and surface them on each
  // CartDiscountCode (errorCode/errorMessage). In practice a single code is applied at a time → 1:1.
  final List warnings = payload['warnings'] ?? const [];
  if (warnings.isEmpty) return cart;
  int w = 0;
  final codes = <CartDiscountCode?>[];
  for (final c in cart.discountCodes ?? const <CartDiscountCode?>[]) {
    if (c != null && c.applicable == false && w < warnings.length) {
      final warning = warnings[w++];
      codes.add(c.copyWith(
        errorCode: warning['code'] as String?,
        errorMessage: warning['message'] as String?,
      ));
    } else {
      codes.add(c);
    }
  }
  return cart.copyWith(discountCodes: codes);
}