XSLT if - Complete XSLT Tutorial

❓ What is <xsl:if>?

The <xsl:if> element tests a condition and processes content only when the condition is true. It's used for simple conditional logic in your XSLT transformations.


<!-- Display only if price is low -->
<xsl:if test="price &lt; 50">
    <p>On Sale!</p>
</xsl:if>

Understanding <if>

The <xsl:if> element evaluates a test condition using XPath expressions. If the condition is true, the content inside is processed. Unlike programming languages, XSLT's if has no else clause - use <xsl:choose> for that.

✅

Test Attribute

Condition to evaluate

test="price > 100"

🔍

XPath Conditions

Use XPath expressions

test="@status='active'"

🎯

Boolean Logic

True/false evaluation

test="count(item) > 0"

⚡

No Else Clause

Only processes if true

<xsl:if test="...">
  <!-- content -->
</xsl:if>

🔹 Basic Condition Example

Display a message only when a condition is met:

XML Data:

<?xml version="1.0"?>
<products>
    <product>
        <name>Laptop</name>
        <price>899</price>
    </product>
    <product>
        <name>Mouse</name>
        <price>25</price>
    </product>
</products>

XSLT Template:

<xsl:template match="products">
    <xsl:for-each select="product">
        <div>
            <h3><xsl:value-of select="name"/></h3>
            <p>Price: $<xsl:value-of select="price"/></p>
            
            <xsl:if test="price &lt; 100">
                <p style="color: red;">🔥 Great Deal!</p>
            </xsl:if>
        </div>
    </xsl:for-each>
</xsl:template>

Output:

Laptop

Price: $899

Mouse

Price: $25

🔥 Great Deal!

🔹 Testing Attributes

Check attribute values with conditional logic:

XML Data:

<users>
    <user status="active">
        <name>John Doe</name>
    </user>
    <user status="inactive">
        <name>Jane Smith</name>
    </user>
</users>

XSLT Template:

<xsl:template match="users">
    <ul>
        <xsl:for-each select="user">
            <li>
                <xsl:value-of select="name"/>
                
                <xsl:if test="@status='active'">
                    <span style="color: green;"> ✓ Active</span>
                </xsl:if>
            </li>
        </xsl:for-each>
    </ul>
</xsl:template>

Output:

John Doe ✓ Active
Jane Smith

🔹 Comparison Operators

Use various operators to test conditions:

Common Operators:

= - Equal to
!= - Not equal to
< - Less than (use < for <)
> - Greater than (use > for >)
<= - Less than or equal
>= - Greater than or equal

XML Data:

<students>
    <student>
        <name>Alice</name>
        <grade>95</grade>
    </student>
    <student>
        <name>Bob</name>
        <grade>72</grade>
    </student>
</students>

XSLT Template:

<xsl:template match="students">
    <xsl:for-each select="student">
        <p>
            <xsl:value-of select="name"/>: 
            <xsl:value-of select="grade"/>
            
            <xsl:if test="grade &gt;= 90">
                <strong> - Excellent!</strong>
            </xsl:if>
            
            <xsl:if test="grade &lt; 75">
                <em> - Needs Improvement</em>
            </xsl:if>
        </p>
    </xsl:for-each>
</xsl:template>

Output:

Alice: 95 - Excellent!

Bob: 72 - Needs Improvement

🔹 Testing Node Existence

Check if a node exists before processing:

XML Data:

<books>
    <book>
        <title>XML Guide</title>
        <author>John Smith</author>
    </book>
    <book>
        <title>Mystery Novel</title>
    </book>
</books>

XSLT Template:

<xsl:template match="books">
    <xsl:for-each select="book">
        <div>
            <h4><xsl:value-of select="title"/></h4>
            
            <xsl:if test="author">
                <p>By: <xsl:value-of select="author"/></p>
            </xsl:if>
            
            <xsl:if test="not(author)">
                <p><em>Author Unknown</em></p>
            </xsl:if>
        </div>
    </xsl:for-each>
</xsl:template>

Output:

XML Guide

By: John Smith

Mystery Novel

Author Unknown

🔹 Logical Operators

Combine multiple conditions using and/or:

XML Data:

<products>
    <product category="Electronics" inStock="yes">
        <name>Laptop</name>
        <price>899</price>
    </product>
    <product category="Electronics" inStock="no">
        <name>Tablet</name>
        <price>499</price>
    </product>
</products>

XSLT Template:

<xsl:template match="products">
    <xsl:for-each select="product">
        <p>
            <xsl:value-of select="name"/> - 
            $<xsl:value-of select="price"/>
            
            <xsl:if test="@category='Electronics' and @inStock='yes'">
                <span style="color: green;"> ✓ Available Now</span>
            </xsl:if>
        </p>
    </xsl:for-each>
</xsl:template>

Output:

Laptop - $899 ✓ Available Now

Tablet - $499

💡 Key Points:

Use test attribute to specify the condition
No else clause - use <xsl:choose> for if-else logic
Use < for < and > for > in XML
Combine conditions with and / or
Use not() function to negate conditions

XSLT <if>

❓ What is <xsl:if>?

Understanding <if>

Test Attribute

XPath Conditions

Boolean Logic

No Else Clause

🔹 Basic Condition Example

XML Data:

XSLT Template:

Output:

Laptop

Mouse

🔹 Testing Attributes

XML Data:

XSLT Template:

Output:

🔹 Comparison Operators

Common Operators:

XML Data:

XSLT Template:

Output:

🔹 Testing Node Existence

XML Data:

XSLT Template:

Output:

XML Guide

Mystery Novel

🔹 Logical Operators

XML Data:

XSLT Template:

Output:

💡 Key Points:

🧠 Test Your Knowledge

Which attribute is required for <xsl:if>?