Overriding the Base Datatype - xsi:type

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) 2013, HerongYang.com, All Rights Reserved.

 <!-- using the base datatype -->
  <name>Herong Yang</name>

 <!-- using the derived datatype "phoneContactType" -->
 <contact xsi:type="phoneContactType">
  <name>Traffic Hotline</name>

 <!-- using the derived datatype "emailContactType" -->
 <contact xsi:type="emailContactType">
  <name>Suggestion Box</name>

Obviously, directory.xml will pass the schema validation as shown below:

>java XsdSchemaValidator directory.xsd directory.xml


Last update: 2013.

Table of Contents

 About This Book

 Introduction to XML Schema

 XML Editor and Schema Processor - XMLPad

 Java API for XML Processing - JAXP

 JAXP - XML Schema (XSD) Validation

 Xerces2 Java Parser - Java API of XML Parsers

 Using Xerces2 Java API

 XML Schema Language - Basics

 Introduction of XSD Built-in Datatypes

 "string" and Its Derived Datatypes

 "decimal" and Its Derived Datatypes

 "dateTime" and Its Related Datatypes

 Miscellaneous Built-in Datatypes

 Facets, Constraining Facets and Restriction Datatypes

 "simpleType" - Defining Your Own Simple Datatypes

 Complex Element Declaration

 Identity-Constraints: unique, key and keyref

 Assertion as Custom Validation Rules

 XML Schema Location and Namespace in XML Documents

Overriding Element Types in XML Documents

 Overriding Element Type to Empty Content - nillable

 Overriding Element Type to Empty Content - xsi:nil

 Defining a Derived Datatype from a Base Datatype

Overriding the Base Datatype - xsi:type

 Overriding the Base Datatype - Errors

 Linking Multiple Schema Documents Together



 PDF Printing Version