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Sometimes you need a way to enter tabular data such as list of quantity for products in a shopping cart, marks from a list of examination candiates, etc. If you just have one input value per line item, you can use a HashMap to store the value. This can be expanded to support multiple input values by having multiple HashMap. This describes a number of alternatives using some of more advanced features of WebWork. Assume you want to capture the quantity and a gift note for a list of products in a shopping cart (i.e Amazon).

1. When the number of line items is known

the cart.vm file

#foreach ( $item in $cart.items )
  #set($index = $velocityCount - 1)
  <input type="hidden" name="cart.items[$index].productId" value="$item.productId">
  <input type="text" name="cart.items[$index].qty" value="$item.qty">
  <input type="text" name="cart.items[$index].note" value="$item.note">
#end

the UpdateCartAction.class

public class UpdateCartAction extends ActionSupport {

	public Cart getCart() {
		return ActionContext.getContext().getSession("cart.key");
	}

	public String execute() throws Exception {
		Cart cart = getCart();

		// loop through a
	}
}

the Cart.class

public class Cart implements Serializable {
  private List items = new ArrayList();

  public List getItems() {
    return items;
  } 

  public void addItem(CartItem item) {
      ...
  }
}

the CartItem.class

public class CartItem implements Serializable {
  private int qty;
  private int productId;
  private String note;

  // getters/setters...
}

Explanation

The resulting vm file is rendered as 

<input type="hidden" name="cart.items[0].qty.productId" value="1">
<input type="text" name="cart.items[0].qty" value="2">
<input type="text" name="cart.items[0].note" value="This is a fun book!">

<input type="hidden" name="cart.items[1].qty.productId" value="2">
<input type="text" name="cart.items[1].qty" value="2">
<input type="text" name="cart.items[1].note" value="You love this one">

<input type="hidden" name="cart.items[2].qty.productId" value="3">
<input type="text" name="cart.items[2].qty" value="$item.qty">
<input type="text" name="cart.items[2].note" value="">

Webwork will populate all the entries in Cart with the correct values.

2. When the number of line items is unknown

For example, you want to allow the user to enter any number of ISBN, quanty and a note. You can replace ArrayList with XWorkList, which will automatically create new items if the index is greater than the size of the list.

3. Use Type Conversion

If you want more advanced way to do this, check out Null Property Access for type conversion.

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