XSLT how to handle XML and node set content in variables

It is very helpful to persist a xml node in a variable that we can query later using xpath, we can accomplish this easily, however you have to make sure the XML transformer (I use Xalan) you are using has to be compatible.

Having the following xml document to play around:

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01	<itemlist>

02	<itemelement>

03	<itemid>1</itemid>

04	<itemname>Article1</itemname>

05	<itemdesc>This is article 1</itemdesc>

06	</itemelement>

07	<itemelement>

08	<itemid>2</itemid>

09	<itemname>Article2</itemname>

10	<itemdesc>This is article 2</itemdesc>

11	</itemelement>

12	<itemelement>

13	<itemid>3</itemid>

14	<itemname>Article3</itemname>

15	<itemdesc>This is article 3</itemdesc>

16	</itemelement>

17	</itemlist>

1.- How to use a XSLT variable that holds a XPATH node set so we can use it as a variable in our XSLT.
1.1.- Build the variable using xpath and only get the node set that is required using a predicate
1.2.- Use the variable same way we use xpath expression Here is the xslt:

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01	<?xml version="1.0" encoding="UTF-8"?>

02	<xsl:stylesheet version="1.0"

03	xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

04

05	<xsl:variable name="vItem"

06	select="/itemList/itemElement[itemId=1]"/>

07

08	<!-- output goes to a text file instead of xml -->

09	<xsl:output method="text" encoding="UTF-8"/>

10

11	<xsl:template match="/">

12	<xsl:text>Name: </xsl:text><xsl:value-of select="$vItem/itemName" />

13	<xsl:text> </xsl:text><!-- line break -->

14	<xsl:text>Desc: </xsl:text><xsl:value-of select="$vItem/itemDesc" />

15	</xsl:template>

16

17	</xsl:stylesheet>

Here is the output:
Name: Article1
Desc: This is article 1

Notes: You might need to include this in the namespace depending on which transformer you are using:

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1	extension-element-prefixes="exsl"

This is an extension that allows to manipulate xml documents within a variable.