This section describes a tutorial example on how to override the element base datatype with a derived datatype by using 'xsi:type'.
To override the base datatype when constructing an XML element, you need to remember the following rules:
1. In the schema, the derived datatype must be defined based on the base datatype.
2. Declare a new namespace prefix in the XML document called, "xsi", with a special attribute on the root element:
"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"". This is needed to provide the namespace prefix "xsi" for the next change.
3. In XML document, add the special attribute "xsi:type="derived-datatype"" to the element.
4. The element's attributes, text content, and child elements must conform to the specified the derived datatype.
Below is a tutorial sample XML document directory.xml that shows you how to override the base datatype with
the special attribute "xsi:type":
<?xml version="1.0"?>
<directory xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<!-- directory.xml
- Copyright (c) 2007 by Dr. Herong Yang. All rights reserved.
-->
<!-- using the base datatype -->
<contact>
<name>Herong Yang</name>
</contact>
<!-- using the derived datatype "phoneContactType" -->
<contact xsi:type="phoneContactType">
<name>Traffic Hotline</name>
<phone>1-866-MY-TRAFC</phone>
</contact>
<!-- using the derived datatype "emailContactType" -->
<contact xsi:type="emailContactType">
<name>Suggestion Box</name>
<email>suggestion@google.com</email>
</contact>
</directory>
Obviously, directory.xml will pass the schema validation as shown below:
