ASP.NET 4 Unleashed

Specifying UpdatePanel Triggers

By default, an UpdatePanel hijacks any postbacks that any of its child controls performs. For example, if a Button control is contained in an UpdatePanel, the UpdatePanel hijacks the button Click event and performs an Ajax call instead of the normal postback.

You can cause an UpdatePanel to refresh its contents from a control located outside of the UpdatePanel by specifying a trigger. For example, the page in Listing 38.5 contains a Button control outside of an UpdatePanel that causes the UpdatePanel to refresh its content.

Listing 38.5. TriggerUpdatePanel.aspx

The UpdatePanel in Listing 38.5 includes a Triggers ...