XSLT, 2nd Edition

Datatypes in XPath 2.0

The XPath 2.0 data model is perhaps the most significant change to writing XSLT version 2.0 stylesheets. We’ll cover the datatypes supported by XPath 2.0. XPath 2.0 supports all of the basic datatypes defined in XML Schema, and a schema-aware XSLT 2.0 processor lets you create your own datatypes. We’ll start with the basic datatypes; these are the only datatypes supported by a basic XSLT processor. To support other datatypes, including datatypes we define (po:purchaseOrder, for example) and derived types defined in XML Schema (such as xs:nonNegativeInteger), you need a schema-aware XSLT processor.

We’ve already looked at using <xsl:variable name="sample" select="'3'" as="xs:integer"/> as a way of creating an xs:integer value. XPath 2.0 also provides constructor functions, described in the following list. For example, <xsl:variable name="sample" select="xs:integer(3)"/> creates a new xs:integer value, whereas <xsl:variable name="birthday" select="xs:date('1995-04-21')"/> creates a new xs:date value:

xs:string

The xs:string datatype represents a string. Every datatype supported by XPath 2.0 has a string representation. If you want to see how a datatype looks as a string, the XSLT <xsl:value-of> element will do the trick. You can convert anything to a string by using the constructor function xs:string(). The constructor is the equivalent of the Java toString() method that’s inherited by every class.

xs:boolean

As in XSLT 1.0, the string values true and false don’t ...