XSLT Transformations

50 min

XSLT (eXtensible Stylesheet Language Transformations) transforms XML documents into other formats (HTML, text, other XML), enabling you to convert XML data into presentation formats or restructure XML. XSLT is a declarative language—you describe the desired output structure, and XSLT determines how to transform the input. XSLT stylesheets are XML documents that define transformation rules. Understanding XSLT enables you to convert and restructure XML effectively. XSLT is powerful for generating HTML from XML data.

XSLT uses XPath to select and process XML elements, enabling you to navigate the source XML tree and extract data. XPath expressions in XSLT select nodes to process. XSLT templates match XPath patterns and define output for matched nodes. Understanding XPath in XSLT enables you to write effective transformations. XPath is essential for XSLT—you use it to select source nodes.

XSLT can convert XML to HTML (for web display), text (for reports), or other XML formats (for data restructuring). XSLT is commonly used to generate HTML from XML data, creating dynamic web content. XSLT can also generate text reports, CSV files, or restructured XML. Understanding XSLT's output capabilities enables you to choose appropriate transformations. XSLT is versatile for format conversion.

XSLT templates define transformation rules, matching source nodes with XPath patterns and generating output. Templates use `xsl:template match="pattern"` to match nodes and define output. Templates can call other templates, enabling modular transformations. Understanding templates enables you to structure XSLT stylesheets effectively. Templates are the core of XSLT transformation logic.

XSLT elements include `xsl:for-each` (iterating over nodes), `xsl:value-of` (extracting values), `xsl:if` and `xsl:choose` (conditional processing), `xsl:apply-templates` (applying templates), and `xsl:sort` (sorting). These elements enable complex transformations. Understanding XSLT elements enables you to write sophisticated stylesheets. XSLT provides powerful transformation capabilities.

Best practices include using templates for modularity, testing transformations, understanding XPath for node selection, organizing stylesheets clearly, and validating output. Understanding XSLT enables you to transform XML effectively. XSLT is powerful but can be complex—start with simple transformations and build complexity gradually. XSLT remains useful for XML transformation tasks.

Key Concepts

XSLT transforms XML documents into other formats.
XSLT uses XPath to select and process XML elements.
XSLT can convert XML to HTML, text, or other XML formats.
XSLT templates define transformation rules.
XSLT elements enable complex transformations.

Learning Objectives

Master

Creating XSLT stylesheets for XML transformation
Using XPath in XSLT to select nodes
Transforming XML to HTML and other formats
Using XSLT templates and elements

Develop

Understanding XML transformation
Designing effective XSLT stylesheets
Appreciating XSLT's role in XML processing

Tips

Use templates for modular, maintainable XSLT stylesheets.
Understand XPath—it's essential for XSLT.
Test transformations with sample XML documents.
Start with simple transformations before tackling complex ones.

Common Pitfalls

Not understanding XPath, making XSLT difficult.
Creating overly complex stylesheets when simpler ones would work.
Not testing transformations, producing incorrect output.
Not organizing templates, making stylesheets hard to maintain.

Summary

XSLT transforms XML documents into other formats.
XSLT uses XPath to select and process XML elements.
XSLT can convert XML to HTML, text, or other XML formats.
Understanding XSLT enables effective XML transformation.
XSLT templates and elements enable complex transformations.

Exercise

Create an XSLT stylesheet to transform XML to HTML.

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="/">
    <html>
      <head>
        <title>Book Catalog</title>
        <style>
          table { border-collapse: collapse; width: 100%; }
          th, td { border: 1px solid black; padding: 8px; text-align: left; }
          th { background-color: #f2f2f2; }
        </style>
      </head>
      <body>
        <h1>Book Catalog</h1>
        <table>
          <tr>
            <th>Title</th>
            <th>Author</th>
            <th>Year</th>
            <th>Price</th>
          </tr>
          <xsl:for-each select="catalog/book">
            <tr>
              <td><xsl:value-of select="title"/></td>
              <td><xsl:value-of select="author"/></td>
              <td><xsl:value-of select="year"/></td>
              <td>$<xsl:value-of select="price"/></td>
            </tr>
          </xsl:for-each>
        </table>
      </body>
    </html>
  </xsl:template>
</xsl:stylesheet>

XSLT Transformations