| Microsoft XML Core Services (MSXML) 5.0 for Microsoft Office - XSLT Developer's Guide |  |
Defining Conditional Templates Using <xsl:if>
The XML file in the example below contains portfolio data. The <stock> element has an exchange attribute. Suppose you want to generate some output only when this attribute has a certain value. You can create another row in the table, and put the attribute value in this row. Alternatively, you can indicate stocks from a particular exchange by noting them with an asterisk (*).
The <xsl:if> element provides a mechanism for conditionally inserting structure into the output tree. In the following example, the <xsl:if> element inserts an asterisk after the symbol for those stocks listed on the NASDAQ stock exchange. The contents of <xsl:if> can be simple text, as in this example, or any structure allowed by XSLT, such as elements or attributes.
In the sample XSLT file below, the test attribute takes a pattern. If the query described by the pattern selects one or more nodes, the <xsl:if> template is inserted. If the selection is empty, the conditional is skipped. In this case, the query checks to see if the <stock> element has an exchange attribute. If so, the query then checks to see if the value of the exchange attribute is equal to "nasdaq".
For more information about qualifying a pattern using brackets ([]) and constructing patterns that compare values, see Introduction to XPath Syntax.
Example
XML File (portfolio-if.xml)
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="portfolio-if.xsl"?>
<portfolio xmlns:dt="urn:schemas-microsoft-com:datatypes" xml:space="preserve">
<stock exchange="nyse">
<name>zacx corp</name>
<symbol>ZCXM</symbol>
<price dt:dt="number">28.875</price>
</stock>
<stock exchange="nasdaq">
<name>zaffymat inc</name>
<symbol>ZFFX</symbol>
<price dt:dt="number">92.250</price>
</stock>
<stock exchange="nasdaq">
<name>zysmergy inc</name>
<symbol>ZYSZ</symbol>
<price dt:dt="number">20.313</price>
</stock>
</portfolio>
XSLT File (portfolio-if.xsl)
<?xml version='1.0'?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:template match="/">
<HTML>
<BODY>
<TABLE BORDER="2">
<TR>
<TD>Symbol</TD>
<TD>Name</TD>
<TD>Price</TD>
</TR>
<xsl:for-each select="portfolio/stock">
<TR>
<TD>
<xsl:value-of select="symbol"/>
<xsl:if test="@exchange[.='nasdaq']">*</xsl:if>
</TD>
<TD><xsl:value-of select="name"/></TD>
<TD><xsl:value-of select="price"/></TD>
</TR>
</xsl:for-each>
</TABLE>
<P>* Listed on Nasdaq stock exchange</P>
</BODY>
</HTML>
</xsl:template>
</xsl:stylesheet>
Formatted Output
