XSLT Parameters

Article
09/15/2021

XSLT parameters are added to the XsltArgumentList using the AddParam method. A qualified name and namespace URI are associated with the parameter object at that time.

To use an XSLT parameter

Create an XsltArgumentList object and add the parameter using the AddParam method.
Call the parameter from the style sheet.
Pass the XsltArgumentList object to the Transform method.

Parameter Types

The parameter object should correspond to a W3C type. The following table shows the corresponding W3C types, the equivalent Microsoft .NET classes (type), and whether the W3C type is an XPath type or XSLT type.

W3C type	Equivalent .NET class (type)	XPath or XSLT type
`String`	System.String	XPath
`Boolean`	System.Boolean	XPath
`Number`	System.Double	XPath
`Result Tree Fragment`	System.Xml.XPath.XPathNavigator	XSLT
`Node*`	System.Xml.XPath.XPathNavigator	XPath
`Node Set`	XPathNodeIterator XPathNavigator[]	XPath

*This is equivalent to a node set that contains a single node.

If the parameter object is not one of the above classes, it is converted according to the following rules. Common language runtime (CLR) numeric types are converted to Double. The DateTime type is converted to String. IXPathNavigable types are converted to XPathNavigator. XPathNavigator[] is converted to XPathNodeIterator.

All other types throw an error.

Example

The following example uses the AddParam method to create a parameter to hold calculated discount date. The discount date is calculated to be 20 days from the order date.

using System;
using System.IO;
using System.Xml;
using System.Xml.XPath;
using System.Xml.Xsl;

public class Sample {

   public static void Main() {

      // Create the XslCompiledTransform and load the style sheet.
      XslCompiledTransform xslt = new XslCompiledTransform();
      xslt.Load("discount.xsl");

      // Create the XsltArgumentList.
      XsltArgumentList argList = new XsltArgumentList();

      // Calculate the discount date.
      DateTime orderDate = new DateTime(2004, 01, 15);
      DateTime discountDate = orderDate.AddDays(20);
      argList.AddParam("discount", "", discountDate.ToString());

      // Create an XmlWriter to write the output.
     XmlWriter writer = XmlWriter.Create("orderOut.xml");

     // Transform the file.
     xslt.Transform(new XPathDocument("order.xml"), argList, writer);
     writer.Close();
  }
}

Imports System.IO
Imports System.Xml
Imports System.Xml.XPath
Imports System.Xml.Xsl

public class Sample

    public shared sub Main()

        ' Create the XslCompiledTransform and load the style sheet.
        Dim xslt as XslCompiledTransform = new XslCompiledTransform()
        xslt.Load("discount.xsl")

        ' Create the XsltArgumentList.
        Dim argList as XsltArgumentList = new XsltArgumentList()

        ' Calculate the discount date.
        Dim orderDate as DateTime = new DateTime(2004, 01, 15)
        Dim discountDate as DateTime = orderDate.AddDays(20)
        argList.AddParam("discount", "", discountDate.ToString())

        ' Create an XmlWriter to write the output.             
        Dim writer as XmlWriter = XmlWriter.Create("orderOut.xml")

        ' Transform the file.
        xslt.Transform(new XPathDocument("order.xml"), argList, writer)
        writer.Close()

    end sub

end class

Input

order.xml

<!--Represents a customer order-->
<order>
  <book ISBN='10-861003-324'>
    <title>The Handmaid's Tale</title>
    <price>19.95</price>
  </book>
  <cd ISBN='2-3631-4'>
    <title>Americana</title>
    <price>16.95</price>
  </cd>
</order>

discount.xsl

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:param name="discount"/>
  <xsl:template match="/">
    <order>
      <xsl:variable name="sub-total" select="sum(//price)"/>
      <total><xsl:value-of select="$sub-total"/></total>
           15% discount if paid by: <xsl:value-of select="$discount"/>
     </order>
  </xsl:template>
</xsl:stylesheet>

Output

<?xml version="1.0" encoding="utf-8"?>  
<order>  
  <total>36.9</total>  
     15% discount if paid by: 2/4/2004 12:00:00 AM  
</order>

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