Here is a brief summary how we can send a text
message to webpage by a web user control.
Delegates is the slolution. There are many good articles on .net delegates you can refer some of them below.
The scenario is we want to send a text
message to the page on completion of some activity on webcontrol.
1/ Create a Base class for webcontrol (refer code below), assuming we are passing some text messages to page from web user control
- Declare a delegate
- Declare an event of type delegate
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;
//Declaring delegate with
message parameter
public delegate void SendMessageToThePageHandler(string messageToThePage);
public
}
class ControlBase: System.Web.UI.UserControl
{
public ControlBase()
{
// TODO: Add constructor logic here
}protected override void OnInit(EventArgs e)
{
base.OnInit(e);
}private string strMessageToPass;/// <summary>
/// MessageToPass - Property to pass text
message to page
/// </summary>
public string MessageToPass
{
get { return strMessageToPass; }
set { strMessageToPass = value; }
}/// <summary>
/// SendMessageToPage - Called from control to invoke the event
/// </summary>
/// <param name="strMessage">Message to pass</param>
public void SendMessageToPage(string strMessage)
{
if (this.sendMessageToThePage != null)
this.sendMessageToThePage(strMessage);
}
2/ Register events on webpage on page Load eventthis.AddControlEventHandler((ControlBase)WebUserControl1);
this.AddControlEventHandler((ControlBase)WebUserControl2);
/// <summary>
/// AddControlEventHandler- Hooking web user control event
/// </summary>
/// <param name="ctrl"></param>
private void AddControlEventHandler(ControlBase ctrl)
{
ctrl.sendMessageToThePage += delegate(string strMessage)
{
//display
message
lblMessage.Text = strMessage;
};
}
References:
http://www.akadia.com/services/dotnet_delegates_and_events.html
3/
