XSL Preserve Space Element

I. Introduction

The XSL Preserve Space Element plays a crucial role in defining how whitespace is handled in XML documents during XSLT processing. This element helps maintain the intended structure and visual formatting of the XML content when it is transformed into another format, such as HTML, ensuring that the output remains faithful to the input.

II. Syntax

A. Basic Syntax Structure

The basic syntax for the preserve-space element is simple. It is written as follows:

    
      <xsl:preserve-space elements="*"/>

B. Attributes Associated with the Preserve-Space Element

The preserve-space element primarily has one key attribute, which specifies which elements in the XML should preserve whitespace.

III. Attributes

A. Exclude-Result-Prefixes Attribute

The exclude-result-prefixes attribute is used to exclude certain namespaces from being part of the output document. The attribute syntax looks like this:

    
      <xsl:preserve-space exclude-result-prefixes="ns1 ns2"/>

B. Required Attributes for Proper Functionality

The only required attribute is elements, which specifies the names of elements that should preserve whitespace.

IV. Usage

A. How to Use the Preserve-Space Element in an XSLT Stylesheet

The preserve-space element must be declared in the stylesheet before any transformation occurs. It is typically placed at the beginning of the XSLT stylesheet.

B. Examples of Practical Applications

Using the preserve-space element is essential when working with markup that has significant whitespace, such as formatting in text or code snippets.

V. Example

A. Sample XML Document

    
      <bookstore>
        <book>
          <title>XML Developer's Guide</title>
          <author>Gambardella, Matthew</author>
          <price>44.95</price>
        </book>
        <book>
          <title>Midnight Rain</title>
          <author>Ralls, Kim</author>
          <price>5.95</price>
        </book>
      </bookstore>

B. Corresponding XSLT Stylesheet with Preserve-Space

    
      <?xml version="1.0" encoding="UTF-8"?>
      <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

        <xsl:preserve-space elements="title author"/>
        
        <xsl:template match="/bookstore">
          <html>
            <body>
              <h1>Bookstore</h1>
              <table border="1">
                <tr>
                  <th>Title</th>
                  <th>Author</th>
                  <th>Price</th>
                </tr>
                <xsl:for-each select="book">
                  <tr>
                    <td><xsl:value-of select="title"/></td>
                    <td><xsl:value-of select="author"/></td>
                    <td><xsl:value-of select="price"/></td>
                  </tr>
                </xsl:for-each>
              </table>
            </body>
          </html>
        </xsl:template>
      
      </xsl:stylesheet>

C. Output Results and Explanation

The output of the above XSLT transformation when applied to the sample XML document will produce an HTML table displaying the books with their titles, authors, and prices. By using the preserve-space element, the formatting in certain values (like title and author) would be consistently maintained, especially if they contained significant whitespace.

VI. Browser Support

While most modern browsers support XSLT processing and the use of the preserve-space element, there are some variations. It’s important to test your XSLT in different browsers to ensure consistent behavior.

Browser	XSLT Support	Preserve-Space Support
Chrome	Yes	Yes
Firefox	Yes	Yes
Safari	Yes	Yes
Internet Explorer	Limited	Limited

VII. Conclusion

The preserve-space element is a powerful tool for developers working with XML and XSLT. It ensures that whitespace handling is accurate during transformations, maintaining the integrity of the data. I encourage you to implement the preserve-space element in your XML transformations to enhance the readability and correctness of your output.

FAQ

Q1: What does the preserve-space element do?

A1: The preserve-space element is used to specify which elements in an XML document should retain whitespace when transforming with XSLT.

Q2: Can I use preserve-space with any XML element?

A2: Yes, you can specify any XML elements to preserve whitespace using their names in the elements attribute of the preserve-space tag.

Q3: Is preserve-space supported in all browsers?

A3: Most modern browsers support preserve-space, but it is advisable to test in various browsers as support may vary, particularly in older versions.

Q4: How do I know if my XML transformation is working correctly?

A4: You can test your XSLT using online tools or in web development environments that support XSLT transformation to see if the whitespace is preserved as expected.

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