Exposing Events in User Controls

Exposing Events in User Controls

A user control can contain the same event-handling subroutines as a normal ASP.NET page. For example, you can add a Page_Load subroutine to a user control that executes before any content in the body of the control is rendered. The Page_Load subroutine contained in the user control is completely distinct from the Page_Load subroutine in the parent page.

The user control in Listing 5.16 randomly displays one of three quotes every time it is displayed.

Listing 5.16 UserControlEvents.ascx

 <Script Runat="Server"> Sub Page_Load   Dim RanNum As New Random   Select Case RanNum.Next( 3 )   Case 0     lblQuote.Text = "A penny saved is a penny earned"   Case 1     lblQuote.Text = "Look before you leap"   Case 2     lblQuote.Text = "He who hesitates is lost"   End Select End Sub </Script> <asp:Label   id="lblQuote"   Runat="Server" /> 

The C# version of this code can be found on the CD-ROM.

The page in Listing 5.17 uses this user control to randomly display a quotation.

Listing 5.17 DisplayControlEvents.aspx

 <%@ Register TagPrefix="SuperCompany" TagName="Quote"   Src="ControlEvents.ascx" %> <SuperCompany:Quote   Runat="Server" /> 

The C# version of this code can be found on the CD-ROM.