What is XSLT Transform?
An XSLT transform is the process of applying an XSLT stylesheet to an XML document to produce a new document or presentation of the data. The XSLT stylesheet contains a set of rules and instructions that define how the transformation should occur.
Syntax:
<!-- Example XSLT stylesheet -->
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<!-- Template for matching the root element of the XML document -->
<xsl:template match="/">
<html>
<body>
<h2>Transformed Output</h2>
</body>
</html>
</xsl:template>
<!-- Template for matching specific elements in the XML document -->
<xsl:template match="book">
<p><xsl:value-of select="title"/></p>
</xsl:template>
</xsl:stylesheet>
- The <xsl:stylesheet> element is the root element that declares the XSLT stylesheet.
- The version attribute indicates the XSLT version being used.
- The xmlns:xsl attribute defines the XML namespace for XSLT.
- <xsl:template> elements define templates for matching specific elements in the XML document.
- The match attribute specifies the pattern to match in the XML document.
- <xsl:value-of> is used to extract and output the value of a selected element.
Elements used in XSLT Transform:
1. <xsl:stylesheet>: The root element that encapsulates the entire XSLT stylesheet.
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
2. <xsl:template>: Defines a template rule that specifies how a particular element or set of elements should be transformed.
<!-- This XSL template is designed to match the root element ("/") of the input XML document. -->
<xsl:template match="/">
<html>
<body>
<!-- Heading level 2 for the transformed output -->
<h2>Transformed Output</h2>
</body>
</html>
</xsl:template>
3. <xsl:value-of>: Extracts the value of a selected node or expression and includes it in the output.
<!-- This XSL template is designed to match elements with the class "book" in the input XML document. -->
<xsl:template match="book">
<!-- Div element with the class "book" for styling purposes -->
<div class="book">
<!-- Heading level 2 for the book title -->
<h2><xsl:value-of select="title"/></h2>
<!-- Paragraph for displaying the author of the book -->
<p>Author: <xsl:value-of select="author"/></p>
<!-- Paragraph for displaying the published year of the book -->
<p>Published Year: <xsl:value-of select="publishedYear"/></p>
</div>
</xsl:template>
4. <xsl:apply-templates>: Triggers the processing of child nodes using their corresponding templates.
Example: Apply templates to process child nodes.
<!-- This XSL template matches the root element ("/") of the input XML document. -->
<xsl:template match="/">
<html>
<body>
<!-- Heading level 1 for the transformed content -->
<h1>Transformed Content</h1>
<!-- Applying templates to process child elements of the root -->
<xsl:apply-templates/>
</body>
</html>
</xsl:template>
5. <xsl:for-each>: Iterates over a selected set of nodes and applies a template for each item in the node-set.
<!-- xsl:for-each to iterate over 'book' elements -->
<xsl:template match="/">
<html>
<body>
<h1>Book List</h1>
<!-- Use xsl:for-each to iterate over 'book' elements -->
<xsl:for-each select="library/books/book">
<div class="book">
<h2><xsl:value-of select="title"/></h2>
<p>Author: <xsl:value-of select="author"/></p>
</div>
</xsl:for-each>
</body>
</html>
</xsl:template>
6. <xsl:if>: Provides conditional processing, allowing certain actions to be taken based on a specified condition.
<!-- xsl:if for conditional processing -->
<xsl:template match="book">
<div class="book">
<h2><xsl:value-of select="title"/></h2>
<p>Author: <xsl:value-of select="author"/></p>
<!-- Use xsl:if to conditionally display a message -->
<xsl:if test="publishedYear < 2000">
<p>Older Book</p>
</xsl:if>
</div>
</xsl:template>
7. <xsl:choose> and <xsl:when>: Allows multiple conditions to be tested, with different actions taken based on the first condition that evaluates to true.
<!-- xsl:choose and xsl:when for multiple conditions -->
<!-- This XSL template is designed to match elements named "book" in the input XML document. -->
<xsl:template match="book">
<!-- Styled division for a book with the class "book" -->
<div class="book">
<!-- Heading level 2 for the book title -->
<h2><xsl:value-of select="title"/></h2>
<!-- Paragraph for displaying the author of the book -->
<p>Author: <xsl:value-of select="author"/></p>
<!-- xsl:choose to handle multiple conditions based on publishedYear -->
<xsl:choose>
<!-- Condition for books published before 2000 -->
<xsl:when test="publishedYear < 2000">
<p>Older Book</p>
</xsl:when>
<!-- Condition for books published between 2000 and 2010 -->
<xsl:when test="publishedYear >= 2000 and publishedYear < 2010">
<p>Published between 2000 and 2010</p>
</xsl:when>
<!-- Default condition for recent books -->
<xsl:otherwise>
<p>Recent Book</p>
</xsl:otherwise>
</xsl:choose>
</div>
</xsl:template>
8. <xsl:text>: Defines text content to be included in the output.
<!-- xsl:text to output text content -->
<xsl:template match="book">
<div>
<h2><xsl:value-of select="title"/></h2>
<p>Author: <xsl:value-of select="author"/></p>
<!-- xsl:text to add a line break -->
<xsl:text>
</xsl:text>
<!-- xsl:text to add additional text content -->
<xsl:text>Published Year: </xsl:text>
<xsl:value-of select="publishedYear"/>
</div>
</xsl:template>
9. <xsl:copy>: Copies the current node or a specified node to the output.
<!-- xsl:copy to copy elements -->
<xsl:template match="book">
<!-- xsl:copy to copy the 'book' element to the output -->
<xsl:copy>
<!-- Copy all attributes of the 'book' element -->
<xsl:copy-of select="@*"/>
<!-- Add additional elements or modify existing elements if needed -->
<additionalInfo>Additional Information Here</additionalInfo>
<!-- Process child nodes of the 'book' element -->
<xsl:apply-templates/>
</xsl:copy>
</xsl:template>
10. <xsl:copy-of>: Copies the current node-set or a specified node-set to the output.
<!-- xsl:copy-of to copy nodes -->
<xsl:template match="library">
<!-- xsl:copy-of to copy all child nodes of 'library' to the output -->
<xsl:copy-of select="*"/>
</xsl:template>
11. <xsl:message>: Outputs a message to the application or system.
<!-- xsl:message to output messages -->
<xsl:template match="/">
<!-- xsl:message to output a message -->
<xsl:message>Transformation started!</xsl:message>
<html>
<body>
<h1>Transformed Content</h1>
<!-- Apply other templates or transformation logic as needed -->
<xsl:apply-templates/>
</body>
</html>
<!-- xsl:message to output another message -->
<xsl:message>Transformation completed!</xsl:message>
</xsl:template>
Conclusion
In summary, XSLT transformation serves as a robust mechanism for the stylized presentation of XML data. Proficiency in XSLT enables developers with the ability to convert raw XML data into sophisticated and user-specific outputs. Within the dynamic realm of web development, a distinct comprehension of XSLT has a great significance, serving as an important asset that unlocks a realm of transformative possibilities.