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ASP.NET Example
As was mentioned in Chapter 10, having FreeDB in a relational format allows for as many queries as you can dream up. Just for a fun example, the ASP.NET page shown in Listing 11.4, allows you to enter a CD Title into a TextBox. Once the button is pushed, all of the track names are returned into a DataGrid on the page.Listing 11.4 shows the ASP.NET page, and Listing 11.5 shows the code behind C# file.
Listing 11.4. ASP.NET Page
This HTML is created automatically by the IDE designer. By double-clicking the button, the IDE creates the event handler and attaches it to the button on the ASP.NET page in Listing 11.2 and a private variable for the Web service, the button click handler code is very simplistic.
<%@ Page language="c#"
Codebehind="WebForm1.aspx.cs" AutoEventWireup="false"Inherits="FreeDBWP.WebForm1" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
<title>WebForm1</title>
content="http://schemas.microsoft.com/intellisense/ie5">
<meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">
<meta name="CODE_LANGUAGE" Content="C#">
<meta name="vs_defaultClientScript" content="JavaScript">
<meta name="vs_targetSchema"
content="http://schemas.microsoft.com/intellisense/ie5">
</HEAD>
<body>
<form method="post" runat="server">
<P>
<asp:Label runat="server">Enter CD Title:</asp:Label></P>
<P>
<asp:TextBox runat="server"></asp:TextBox></P>
<P>
<asp:Button runat="server" Text="Get Tracks for CD"></asp:Button></P>
<asp:DataGrid runat="server"></asp:DataGrid>
</form>
</body>
</HTML>
Listing 11.5. Corresponding C# Code Behind File
Figure 11-4. This also ties back to the beginning of the chapter as a great illustration of a server-side button click event handler populating a Datagrid for display to the user.Note the two X terminal windows running postmaster/postgresql and XSP. While this is not the most useful query, it does serve as a good proof of concept for operating system-independent ASP.NET and Web service development.
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
namespace FreeDBWP
{
/// <summary>
/// Summary description for WebForm1.
/// </summary>
public class WebForm1 : System.Web.UI.Page
{
protected System.Web.UI.WebControls.Label Label1;
protected System.Web.UI.WebControls.TextBox TextBox1;
protected System.Web.UI.WebControls.Button Button1;
protected System.Web.UI.WebControls.DataGrid DataGrid1;
private webservice.Service1 ws;
private void Page_Load(object sender, System.EventArgs e)
{
// Put user code to initialize the page here
}
#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: This call is required by the ASP.NET Web Form Designer.
//
InitializeComponent();
base.OnInit(e);
}
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.Button1.Click += new System.EventHandler(this.Button1_Click);
this.Load += new System.EventHandler(this.Page_Load);
}
#endregion
private void Button1_Click(object sender, System.EventArgs e)
{
try
{
if(this.TextBox1.Text.Length>0)
{
ws = new webservice.Service1();
this.DataGrid1.DataSource = ws.GetTracksForCd(this.TextBox1.Text);
this.DataGrid1.DataBind();
}
}
catch(Exception ex)
{
Debug.WriteLine(ex.ToString());
}
}
}
