TransformFile Property

XmlDataSource.TransformFile Property


Specifies the file name of an Extensible Stylesheet Language (XSL) file (.xsl) that defines an XSLT transformation to be performed on the XML data managed by the XmlDataSource control.

Namespace:   System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

public virtual string TransformFile { get; set; }

Property Value

Type: System.String

The absolute physical path or relative path of the XSL style sheet file that defines an XML transformation to be performed on the data contained in the Data or DataFile properties. The default value is String.Empty.

Exception Condition

The document is loading.

If both the TransformFile and Transform properties are set, the TransformFile property takes precedence and the data in the XSL style sheet file (.xsl) is used instead of the style sheet elements specified in the Transform property. If an XPath expression is set using the XPath property, it is applied after the XML data is transformed.

If you change the value of the Transform property, the DataSourceChanged event is raised. If caching is enabled and you change the value of Transform, the cache is invalidated.


The XmlDataSource class uses the deprecated XslTransform class to perform XSL transformations. If you want to use style sheet features that were introduced after the XslTransform class was deprecated, apply the transforms manually by using the XslCompiledTransform class.

The following code example demonstrates how to use an XmlDataSource control and a TreeView control to display transformed XML data on a Web form. The transformation is performed using the style sheet indicated by the TransformFile property. You can optionally supply transformation arguments for the style sheet using an XsltArgumentList. For more information, see the TransformArgumentList property.

<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">

<html xmlns="" >
  <head runat="server">
    <title>ASP.NET Example</title>

    <form id="form1" runat="server">

      <!- TreeView uses hierachical data, so the
          XmlDataSource uses an XmlHierarchicalDataSourceView
          when a TreeView is bound to it. -->

          <asp:treenodebinding depth="1" datamember="genre"
             textfield="name" valuefield="name"/>
          <asp:treenodebinding depth="2" datamember="book"
            textfield="title" valuefield="ISBN"/>
          <asp:treenodebinding depth="3" datamember="chapter"
            textfield="name" valuefield="num"/>



The XML file in the code example has the following data:

   <genre name="fiction">
     <book ISBN="0000000000">
       <title>Secrets of Silicon Valley</title>
         <chapter num="1" name="Introduction" />           
         <chapter num="2" name="Body" />          
         <chapter num="3" name="Conclusion" />
   <genre name="novel">
     <book genre="novel" ISBN="1111111111">
       <title>Straight Talk About Computers</title>
         <chapter num="1" name="Introduction" /> 
         <chapter num="2" name="Body" />
         <chapter num="3" name="Conclusion" />

The XSL style sheet that performs the XML transformation has the following structure:

<xsl:stylesheet version="1.0" xmlns:xsl="">
 <xsl:template match="bookstore">
     <xsl:apply-templates select="genre"/>
 <xsl:template match="genre">
     <xsl:attribute name="name">
       <xsl:value-of select="@name"/>
     <xsl:apply-templates select="book"/>
 <xsl:template match="book">
     <xsl:attribute name="ISBN">
       <xsl:value-of select="@ISBN"/>
     <xsl:attribute name="title">
       <xsl:value-of select="title"/>
     <xsl:attribute name="price">
       <xsl:value-of select="price"/>
     <xsl:apply-templates select="chapters/chapter" />
 <xsl:template match="chapter">
     <xsl:attribute name="num">
       <xsl:value-of select="@num"/>
     <xsl:attribute name="name">
       <xsl:value-of select="@name"/>

.NET Framework
Available since 2.0
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