Average Xml Data using ASP.NET and C#

This tutorial will show you how to calculate average of data from XML using ASP.NET 2.0 and C#.

This tutorial will show you how to calculate average of data from XML using ASP.NET 2.0 and C#. The System.Xml.XPath namespace contains the classes that define a cursor model for navigating and editing XML information items as instances of the XPath 2.0 Data Model. XPath expressions as a string, or a compiled XPathExpression that return a W3C XPath type of boolean (System.Boolean), number (System.Double), string (System.String), or node set (System.Xml.XPath.XPathNodeIterator), can be passed to the Evaluate method. The Evaluate method takes the expression, evaluates it, and returns a typed result. This method could be used in a mathematical user defined method. For example, the following code calculates the total price of all item elements and div number of book  in the current selection.

XPathNavigator class Provides a cursor model for navigating and editing XML data.
XPathDocument  class Provides a fast, read-only cache for XML document processing using XSLT.
XPathNodeIterator class Provides an iterator over a selected set of nodes.

using System.Xml; using System.Xml.XPath; using System.Data.SqlClient;

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The following code of  Button1_Click uses the Evaluate method with the average function.

protected void Button1_Click(object sender, EventArgs e) { docNav = new XPathDocument(Server.MapPath("Books.xml")); nav = docNav.CreateNavigator(); strExpression = "sum(/bookstore/book/price) div count(/bookstore/book/price)"; expression. Label1.Text = nav.Evaluate(strExpression).ToString(); }

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The front end AverageXmlDataCsharp.aspx page looks something like this:

<div> <br /> <table width="600" border="0" align="center" cellpadding="5" cellspacing="1" bgcolor="#5482fc"> <tr> <td height="50" align="center" class="lgHeader1"> How to Average xmldata using ASP.NET 2.0 and C#</td> </tr> </table> <div align="center"> <fieldset style="width: 589px"> <legend>Average Price</legend> <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" CellPadding="4" ForeColor="#333333" GridLines="None"> <FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" /> <Columns> <asp:BoundField DataField="title" HeaderText="Title" /> <asp:BoundField DataField="author" HeaderText="Author" /> <asp:BoundField DataField="price" HeaderText="Price" /> </Columns> <RowStyle BackColor="#EFF3FB" /> <EditRowStyle BackColor="#2461BF" /> <SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" /> <PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" /> <HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" /> <AlternatingRowStyle BackColor="White" /> </asp:GridView> &nbsp; <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Average price" /> <asp:Label ID="Label1" runat="server" Text="Show averagedata from xml document:"></asp:Label></fieldset> </div>

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The flow for the code behind page is as follows.

using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using System.Xml; using System.Xml.XPath; using System.Data.SqlClient; public partial class _Default : System.Web.UI.Page { XPathNavigator nav; XPathDocument docNav; XPathNodeIterator nodeIter; string strExpression; protected void Page_Load(object sender, EventArgs e) { if (!Page.IsPostBack) { DataSet myDs = new DataSet(); myDs.ReadXml(Server.MapPath("Books.xml")); this.GridView1.DataSource = myDs.Tables["book"].DefaultView; this.GridView1.DataBind(); myDs.Clear(); } } protected void Button1_Click(object sender, EventArgs e) { docNav = new XPathDocument(Server.MapPath("Books.xml")); nav = docNav.CreateNavigator(); strExpression = "sum(/bookstore/book/price) div count(/bookstore/book/price)"; Label1.Text = nav.Evaluate(strExpression).ToString(); } }

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