Advanced XSLT: Conditions, Sorting, and Modular Design

Unit 4•CLO04, CLO05

Learning Objectives

Course Learning Outcomes

CLO04

CLO05

Course Outcomes

CO04

CO05

ℹ️

Introduction

Real-world transforms branch, classify, and reuse logic. Conditions, variables, and separate templates keep stylesheets maintainable. You also learn to compute values (totals, averages) and to modularize code.

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The Basics

Control and reuse

xsl:if for single checks; xsl:choose for multi-branch logic.
Variables hold computed values or XPath results (immutable once set).
Named templates enable reuse across documents.
Import/include split large stylesheets for teams.

Technical Details

Snippets worth memorizing

Branching

<xsl:choose>
  <xsl:when test="price &gt; 500">Expensive</xsl:when>
  <xsl:otherwise>Affordable</xsl:otherwise>
</xsl:choose>

Variables and totals

<xsl:variable name="total" select="sum(/library/book/price)"/>
<p>Total: <xsl:value-of select="$total"/></p>

Modularity

<xsl:call-template name="renderRow"/>

Examples

Classification example

<xsl:template match="book">
  <tr>
    <td><xsl:value-of select="title"/></td>
    <td>
      <xsl:choose>
        <xsl:when test="number(price) &gt; 500">High</xsl:when>
        <xsl:otherwise>Low</xsl:otherwise>
      </xsl:choose>
    </td>
  </tr>
</xsl:template>

Sorting with numbers

<xsl:for-each select="library/book">
  <xsl:sort select="number(price)" data-type="number" order="ascending"/>
  <xsl:value-of select="title"/>
</xsl:for-each>

Self-check

Real-World Use

Apply it

Add a price band label using xsl:choose.
Compute a grand total and average with sum() and count().
Move row rendering into a named template and call it, keeping the root template slim.

📝 For exams

Likely questions

Contrast xsl:if with xsl:choose.
How does xsl:sort treat numbers vs strings?
Two advantages of named templates or imports.

✨ Key points

Takeaways

Conditions make transforms context-aware.
Variables simplify repeated calculations.
Modular stylesheets stay maintainable as projects grow.

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XSLT Basics: Templates, Match/Select, and HTML Output

XPath: Node Selection, Axes, Predicates, and Functions

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