Examples

This section shows some code examples of how the json-taglib could be used in real world situations.

Shopping Cart

You need to add AJAX functionality to an e-commerce application. Whenever the user adds an item to their cart, you want to render the new contents of the cart as JSON, so the browser can update the cart display dynamically.

Assume you have a cart object that contains, amongst other things, a collection of lineItems. 

<%@ taglib prefix="json" uri="http://www.atg.com/taglibs/json" %>

<json:object>
  <json:property name="itemCount" value="${cart.itemCount}"/>
  <json:property name="subtotal" value="${cart.subtotal}"/>
  <json:array name="items" var="item" items="${cart.lineItems}">
    <json:object>
      <json:property name="title" value="${item.title}"/>
      <json:property name="description" value="${item.description}"/>
      <json:property name="imageUrl" value="${item.imageUrl"/>
      <json:property name="price" value="${item.price}"/>
      <json:property name="qty" value="${item.qty}"/>
    </json:object>
  </json:array>
</json:object>

...produces this JSON...

{
  itemCount: 2,
  subtotal: "$15.50",
  items:[
    {
      title: "The Big Book of Foo",
      description: "Bestselling book of Foo by A.N. Other",
      imageUrl: "/images/books/12345.gif",
      price: "$10.00",
      qty: 1
    },
    {
      title: "Javascript Pocket Reference",
      description: "Handy pocket-sized reference for the Javascript language",
      imageUrl: "/images/books/56789.gif",
      price: "$5.50",
      qty: 1
    }
  ]
}

Shopping Cart (part 2)

The above example was quite simplistic. If your e-commerce store supported multiple languages and currencies, then it is likely that you would want to show your pricing data using the correct format for that locale.

Here we'll add the JSTL Format tag to render the prices using the appropriate currency formatting.

<%@ taglib prefix="json" uri="http://www.atg.com/taglibs/json" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>

<json:object>
  <json:property name="itemCount" value="${cart.itemCount}"/>
  <json:property name="subtotal">
    <fmt:formatNumber value="${cart.subtotal}" type="currency" currencyCode="${cart.currency}"/>
  </json:property>
  <json:array name="items" var="item" items="${cart.lineItems}">
    <json:object>
      <json:property name="title" value="${item.title}"/>
      <json:property name="description" value="${item.description}"/>
      <json:property name="imageUrl" value="${item.imageUrl"/>
      <json:property name="price">
        <fmt:formatNumber value="${item.price}" type="currency" currencyCode="${cart.currency}"/>
      </json:property>
      <json:property name="qty" value="${item.qty}"/>
    </json:object>
  </json:array>
</json:object>