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XmlDataSource.Transforming Event

Occurs before the style sheet that is defined by the Transform property or identified by the TransformFile property is applied to XML data.

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)
public event EventHandler Transforming
<asp:XmlDataSource OnTransforming="EventHandler" />

Handle the Transforming event to set the TransformArgumentList property with an XsltArgumentList object before the XmlDataSource control performs an XML transformation.

For more information about handling events, see Consuming Events.

The following code example demonstrates how to use an XmlDataSource control with a TreeView control to display transformed XML data. The XML transformation is performed using the style sheet indicated by the TransformFile property. Additionally, the style sheet uses transform arguments that are passed to the data source control in an XsltArgumentList at run time. The code example demonstrates how to pass the XsltArgumentList object to the data source control by handling the Transforming event with a custom event handler.


<%@ Page Language="C#" %>
<%@ Import Namespace="System.Xml.Xsl" %>


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
private void TransformEventHandler(object sender, EventArgs e) {

  // Add a dynamic transformation argument.
  DateTime d = new DateTime();
  d = DateTime.Now.AddDays(20);

  // Create an XsltArgumentList.
  XsltArgumentList xslArg = new XsltArgumentList();
  xslArg.AddParam("purchdate", "", d.ToShortDateString());

  ((XmlDataSource) sender).TransformArgumentList = xslArg;
}
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="form1" runat="server">
      <asp:XmlDataSource
        id="XmlDataSource1"
        runat="server"
        datafile="bookstore.xml"
        transformfile="bookswithdiscount.xsl"
        ontransforming="TransformEventHandler" />

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

      <asp:treeview
        id="TreeView1"
        runat="server"
        datasourceid="XmlDataSource1">
        <databindings>
          <asp:treenodebinding Depth="1" datamember="genre"
            textfield="name" valuefield="name"/>
          <asp:treenodebinding depth="2" datamember="book"
            textfield="title" valuefield="title"/>
          <asp:treenodebinding depth="3" datamember="chapter"
            textfield="name" valuefield="num"/>
        </databindings>
      </asp:treeview>

    </form>
  </body>
</html>


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

<bookstore>
   <genre name="fiction">
     <book ISBN="0000000000">
       <title>Secrets of Silicon Valley</title>
       <price>12.95</price>
       <chapters>
         <chapter num="1" name="Introduction" />           
         <chapter num="2" name="Body" />          
         <chapter num="3" name="Conclusion" />
       </chapters>
     </book>
   </genre>
   <genre name="novel">
     <book genre="novel" ISBN="1111111111">
       <title>Straight Talk About Computers</title>
       <price>24.95</price>
       <chapters>
         <chapter num="1" name="Introduction" /> 
         <chapter num="2" name="Body" />
         <chapter num="3" name="Conclusion" />
       </chapters>
     </book>
   </genre>
</bookstore>

The transformation of the XML data is performed with the following style sheet:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:param name="purchdate"/>
 <xsl:template match="bookstore">
   <bookstore>
     <xsl:apply-templates select="genre"/>
   </bookstore>
 </xsl:template>
 <xsl:template match="genre">
   <genre>
     <xsl:attribute name="name">
       <xsl:value-of select="@name"/>
     </xsl:attribute>
     <xsl:apply-templates select="book"/>
   </genre>
 </xsl:template>
 <xsl:template match="book">
   <book>
     <xsl:attribute name="ISBN">
       <xsl:value-of select="@ISBN"/>
     </xsl:attribute>
     <xsl:attribute name="title">
       <xsl:value-of select="title"/>
       Price: <xsl:value-of select="price"/>
           15% discount if purchased by: <xsl:value-of select="$purchdate"/>      
     </xsl:attribute>
     <xsl:apply-templates select="chapters/chapter" />
   </book>
 </xsl:template>
 <xsl:template match="chapter">
   <chapter>
     <xsl:attribute name="num">
       <xsl:value-of select="@num"/>
     </xsl:attribute>
     <xsl:attribute name="name">
       <xsl:value-of select="@name"/>
     </xsl:attribute>
     <xsl:apply-templates/>
   </chapter>
 </xsl:template>
</xsl:stylesheet>

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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