(Photo: Red Cart Conga, Baby by It’sGreg)

ATG’s CartModifierFormHandler has a handle method for adding multiple items to the shopping cart, handleAddMultipleItemsToOrder.

What is required is that in the request you set the product ID and SKU ID (catalogRefId) for each product you want to add.

Seems pretty-straightforward, right?  Well there are a couple of tricks.

Trick #1: Setting the quantity

Setting the quantity of the amount of each SKU you want added to the cart requiring naming the quantity input using the SKU iD.

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Trick #2: Handling zero quantity inputs

When the handleAddMultipleItemsToOrder tries to add something that has a quantity of zero or less you it will output an error message that the quantity is zero or less.  If you have a input form where the user does not have to add all the items on the page then this will be problematic.

To get around this restriction I overrode the preAddMultipleItemsToOrder method.  My method sets the productIds and catalogRefIds properties to only have items that have a quantity greater than zero.

public void preAddMultipleItemsToOrder(DynamoHttpServletRequest pReq,
    DynamoHttpServletResponse pRes) throws ServletException,
    IOException {

  // get the SKU ID's and product ID's set in the form
  String[] oldCatalogRefIds = getCatalogRefIds();
  String[] oldProductIds = getProductIds();

  // make sure that the SKU ID's and product ID's are valid and of the
  // same length
  if (oldCatalogRefIds == null || oldCatalogRefIds.length == 0)
    return;
  if (oldProductIds == null || oldCatalogRefIds.length != oldProductIds.length) {
    return;
  }

  // initialize list for the SKU ID's and product ID's that we will add to
  // the shopping cart
  List newCatalogRefIdsList = new ArrayList(
      oldCatalogRefIds.length);
  List newProductIdsList = new ArrayList(
      oldCatalogRefIds.length);

  // iterate through original SKU ID's
  for (int ii = 0; ii < oldCatalogRefIds.length; ii++) {

    // get next SKU ID
    String catalogRefId = oldCatalogRefIds[ii];

    // get quantity requested for that SKU ID
    long qty;
    try {
      qty = getQuantity(catalogRefId, pRequest, pResponse);
    } catch (NumberFormatException exc) {
      if (isLoggingDebug())
        logDebug("invalid quantity for catalogRefId=" + catalogRefId, exc);
      qty = 0;
    }

    // if quantity > 0 then save this SKU ID and it's product ID
    if (qty > 0) {
      newCatalogRefIdsList.add(catalogRefId);
      String productId = oldProductIds[ii];
      newProductIdsList.add(productId);
    }
  }

  // set the catalog ID's property to only have the SKU ID's of things
  // that are being ordered
  String[] newCatalogRefIds = new String[newCatalogRefIdsList.size()];
  newCatalogRefIdsList.toArray(newCatalogRefIds);
  if (isLoggingDebug()) {
    logDebug("old catalogRefIds=" + Arrays.toString(oldCatalogRefIds)
        + ", new catalogRefIds="
        + Arrays.toString(newCatalogRefIds));
  }
  setCatalogRefIds(newCatalogRefIds);

  // set the product ID's property to only have the product ID's of things
  // that are being ordered
  String[] newProductIds = new String[newProductIdsList.size()];
  newProductIdsList.toArray(newProductIds);
  if (isLoggingDebug()) {
    logDebug("old productIds=" + Arrays.toString(oldProductIds)
        + ", new productIds="
        + Arrays.toString(newProductIds));
  }
  setProductIds(newProductIds);
}