Building Composite Controls : CompositeControl « Custom Controls « ASP.NET Tutorial

using System;
using System.Web.UI.WebControls;

namespace myControls
{
    public class RequiredTextBox : CompositeControl
    {
        private TextBox input;
        private RequiredFieldValidator validator;

        public string Text
        {
            get
            {
                EnsureChildControls();
                return input.Text;
            }
            set
            {
                EnsureChildControls();
                input.Text = value;
            }
        }

        protected override void CreateChildControls()
        {
            input = new TextBox();
            input.ID = "input";
            this.Controls.Add(input);

            validator = new RequiredFieldValidator();
            validator.ID = "valInput";
            validator.ControlToValidate = input.ID;
            validator.ErrorMessage = "(Required)";
            validator.Display = ValidatorDisplay.Dynamic;
            this.Controls.Add(validator);
        }
    }
}

File: Default.aspx


<%@ Page Language="C#" Trace="true" %>
<%@ Register TagPrefix="custom" Namespace="myControls" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

    protected void btnSubmit_Click(object sender, EventArgs e)
    {
        lblResults.Text = txtUserName.Text;
    }
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Show RequiredTextBox</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>

    <asp:Label
        ID="lblUserName"
        Text="User Name:"
        AssociatedControlID="txtUserName"
        Runat="server" />

    <custom:RequiredTextBox
        ID="txtUserName"
        Runat="Server" />

    <br />

    <asp:Button
        ID="btnSubmit"
        Text="Submit"
        Runat="server" OnClick="btnSubmit_Click" />

    <hr />

    <asp:Label
        id="lblResults"
        Runat="server" />

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

14.20.CompositeControl
	14.20.1.	Building Composite Controls
	14.20.2.	Building Hybrid Controls
	14.20.3.	Performing layout with an HTML table.
	14.20.4.	Item Rotator
	14.20.5.	Image Rotator
	14.20.6.	Creating a Default Template
	14.20.7.	File: Product.cs
	14.20.8.	Supporting Two-Way Databinding
	14.20.9.	Creating Templated Databound Controls