The use of XSLT in ASP.NET 2.0

Author：Eve Cole Update Time：2009-06-30 16:48:40

In asp.net 2.0, the application of XML is greatly enhanced, and new functions are also provided in terms of XSLT processing. This article will briefly explain the use of XSLT in asp.net 2.0. Of course, this article assumes that readers have certain basic knowledge of XSLT.

In asp.net 2.0, there are the following changes and new features in XSLT:

·XslCompiledTransform - It is actually the XslTransform of .NET 1.0, but provides better performance support and also supports the smooth migration of previous applications under .net 1.0.

·XsltArgumentList - allows passing parameters or objects to XSLT

XsltCompileException - Exception generated when an error occurs while loading an XSL document via the loa() method.

XsltException - Exception generated when an error occurs while parsing an XSL document.

Let’s look at a simple example first. This example takes data from the NORTHWIND database, displays it in XML format, and then converts it in XSLT format. The XSLT code is as follows:

＜?xml version="1.0" ?＞
＜xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"＞
＜xsl:output method="html" /＞
<xsl:template match="/">
<HTML>
＜HEAD＞
＜TITLE＞Simple XSLT Transformation＜/TITLE＞
＜/HEAD＞
＜BODY＞
＜H2＞Simple XSLT Transformation＜/H2＞
＜table border="1" cellSpacing="1" cellPadding="1">
＜center＞
＜xsl:for-each select="//Categories"＞

<xsl:element name="tr">
<xsl:element name="td">
＜xsl:value-of select="ProductSubcategoryID" /＞
＜/xsl:element＞
<xsl:element name="td">
＜xsl:value-of select="Name" /＞
＜/xsl:element＞
<xsl:element name="td">
＜xsl:attribute name="align"＞center＜/xsl:attribute＞
＜xsl:value-of select="ModifiedDate" /＞
＜/xsl:element＞
＜/xsl:element＞
＜/xsl:for-each＞
＜/center＞
＜/table＞
＜/BODY＞
＜/HTML＞
＜/xsl:template＞
＜/xsl:stylesheet＞

Then the ASPX code displayed is:

＜%@ Page Language="C#" %＞
＜%@ Import Namespace="System.Data.SqlClient" %＞
＜%@ Import Namespace="System.Xml" %＞
＜%@ Import Namespace="System.Xml.Xsl" %＞
＜%@ Import Namespace="System.Xml.XPath" %＞
＜%@ Import Namespace="System.Web.Configuration" %＞
＜script runat="server"＞
void Page_Load(object sender, System.EventArgs e)
{
string connString = WebConfigurationManager.ConnectionStrings
["adventureWorks"].ConnectionString;
using (SqlConnection connection = new SqlConnection(connString))
{
connection.Open();
SqlCommand command = new SqlCommand
("Select * from Production.ProductSubcategory as Categories " +
" for xml auto,elements", connection);
XmlReader reader = command.ExecuteXmlReader();
XPathDocument xpathDoc = new XPathDocument(reader);
string xslPath = Server.MapPath("Category.xsl");
XslCompiledTransform transform = new XslCompiledTransform();
transform.Load(xslPath);
transform.Transform(xpathDoc, null, Response.Output);
}
}
＜/script＞

Note that we first use xmlreader to read the data extracted from the database (in the form of xml auto), then load the xsl file, and then use the xslcompiledtransform class for conversion, in which xpathdocument is used to improve performance. Note that xslcompiledtransform is used here instead of xslttransform in .net 1.1. The running results are as follows

You can also pass parameters or objects into XSLT. Let’s first look at how to pass parameters into it. For example, if you want to change the background color of the above example, you can write XSLT like this

＜?xml version="1.0" ?＞
＜xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"＞
＜xsl:output method="html" /＞
＜xsl:param name="BackGroundColor" select="Blue" /＞
<xsl:template match="/">
<HTML>
＜HEAD＞
＜TITLE＞Passing Parameters to an XSLT Style Sheet＜/TITLE＞
＜/HEAD＞
＜BODY＞
＜H2＞ Passing Parameters to an XSLT Style Sheet＜/H2＞
＜table border="1" cellSpacing="1" cellPadding="1">
＜center＞
＜xsl:for-each select="//Categories"＞

<xsl:element name="tr">
<xsl:attribute name="bgcolor">
＜xsl:value-of select="$BackGroundColor" /＞
＜/xsl:attribute＞
<xsl:element name="td">
＜xsl:value-of select="ProductSubcategoryID" /＞
＜/xsl:element＞
<xsl:element name="td">
＜xsl:value-of select="Name" /＞
＜/xsl:element＞
<xsl:element name="td">
＜xsl:attribute name="align"＞center＜/xsl:attribute＞
＜xsl:value-of select="ModifiedDate" /＞
＜/xsl:element＞
＜/xsl:element＞
＜/xsl:for-each＞
＜/center＞
＜/table＞
＜/BODY＞
＜/HTML＞
＜/xsl:template＞
＜/xsl:stylesheet＞

What to note is that:

<xsl:attribute name="bgcolor">
＜xsl:value-of select="$BackGroundColor" /＞

The backgroundcolor is specified as a parameter in this form, and at the beginning of the XSLT, a value of blue is set for the backgroundcolor in the form of <xsl:param name="BackGroundColor" select="Blue" />, like this Then set the background color of <tr> to bgcolor=blue to achieve the effect of turning each row of output data into blue.