XSLT `xsl:if` Element: Implementing Conditional Logic in XML Transformations

Master conditional processing in XSLT using the `xsl:if` element. This tutorial explains how to use XPath expressions within the `test` attribute to control which parts of your XML document are transformed based on specified criteria, creating dynamic and targeted output.

Using the XSLT `xsl:if` Element for Conditional Processing

Understanding `xsl:if`

The XSLT `xsl:if` element is used to perform conditional processing of XML data. It evaluates a boolean expression (specified using the `test` attribute). If the expression is true, the content of the `xsl:if` element is processed; otherwise, it's skipped. This is a basic but very useful tool for creating more flexible and dynamic XSLT transformations. It allows you to select or filter nodes based on whether conditions are met, helping to create more targeted and efficient transformations.

`xsl:if` Attribute: `test`

The `test` attribute of the `xsl:if` element is an XPath expression that evaluates to either true or false. If it's true, the contents of the `xsl:if` element are included in the output. If it's false, those contents are omitted.

Example: Conditional Employee Details

This example uses `xsl:if` to display employee details only if their salary is greater than 15000. This shows how to use `xsl:if` to conditionally process XML nodes. The XML data contains employee information; the XSLT stylesheet selects employees meeting the salary criterion.

1. Sample XML Data (`Employee.xml`)

<Employees>
  <Employee id="1">
    <FirstName>Aryan</FirstName>
    <LastName>Gupta</LastName>
    <NickName>Raju</NickName>
    <Salary>30000</Salary>
  </Employee>
  <Employee id="2">
    <FirstName>Sara</FirstName>
    <LastName>Khan</LastName>
    <NickName>Zoya</NickName>
    <Salary>25000</Salary>
  </Employee>
  <Employee id="3">
    <FirstName>Peter</FirstName>
    <LastName>Symon</LastName>
    <NickName>John</NickName>
    <Salary>10000</Salary>
  </Employee>
</Employees>

2. XSLT Stylesheet (`Employee.xsl`)

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="/">
    <table border="1">
      <tr>
        <th>ID</th>
        <th>First Name</th>
        <th>Last Name</th>
        <th>Nick Name</th>
        <th>Salary</th>
      </tr>
      <xsl:for-each select="//Employee">
        <xsl:if test="Salary > 15000">
          <tr>
            <td><xsl:value-of select="@id"/></td>
            <td><xsl:value-of select="FirstName"/></td>
            <td><xsl:value-of select="LastName"/></td>
            <td><xsl:value-of select="NickName"/></td>
            <td><xsl:value-of select="Salary"/></td>
          </tr>
        </xsl:if>
      </xsl:for-each>
    </table>
  </xsl:template>
</xsl:stylesheet>

Conclusion

The `xsl:if` element is a fundamental building block for creating conditional logic in XSLT. It allows you to create more dynamic and flexible transformations based on the data in your XML documents.