Defining ASP.NET Update Panel Template Contents Dynamically
The ASP.NET UpdatePanel was introduced with the ASP.NET 2.0 AJAX Extensions almost a century ago (kidding, but almost feels like it!
). It allows us to have AJAX-style effects (partial page loads) with very little effort.
The UpdatePanel has a property, ContentTemplate, which is, well, a template, which means it can only be set through markup – not so good for dynamic contents -, or by implementing our own ITemplate class – slightly more work, but this can be reused in other scenarios where an ITemplate is required:
public class Template : Control, ITemplate
{public void InstantiateIn(Control container)
{ var controls = this.Controls.OfType<Control>().ToList(); for (var i = 0; i < controls.Count; i++) {var control = controls[i];
container.Controls.Add(control);
}
}
}
protected override void OnLoad(EventArgs e)
{var tb = new TextBox { ID = "time" };
var timer = new Timer { Interval = 1000, Enabled = true };
timer.Tick += timer_Tick;
var tmp = new Template();tmp.Controls.Add(tb);
tmp.Controls.Add(timer);
var up = new UpdatePanel();up.ContentTemplate = tmp;
this.Form.Controls.Add(up); base.OnLoad(e);}
void timer_Tick(object sender, EventArgs e)
{var time = (sender as Control).NamingContainer.FindControl("time") as TextBox;
time.Text = DateTime.Now.ToString();
}
There is also a property, ContentTemplateContainer, which is a control to which you can add your controls, so that they are added to the UpdatePanel. This is exactly what we need:
protected override OnLoad(EventArgs e)
{var tb = new TextBox { ID = "time" };
var timer = new Timer { Interval = 1000, Enabled = true };
timer.Tick += this.timer_Tick; var up = new UpdatePanel();up.ContentTemplateContainer.Controls.Add(tb);
up.ContentTemplateContainer.Controls.Add(timer);
this.Form.Controls.Add(up); base.OnLoad(e);}