Question

I am new to ASP .NET web controls, but not ASP .NET in general or C#.

I am wondering how I can limit the allowed content types to a specific class.

I have made a custom web control called TabPanel, and I want it to only be able to contain TabPages.

As an example, the following markup should be illegal, since it contains a checkbox.

<cc1:TabPanel ID="TabPanel1" runat="server">
    <cc1:TabPage runat="server">
        this is a simple test
    </cc1:TabPage>
    <cc1:TabPage runat="server">
        this is another simple test
    </cc1:TabPage>
    <asp:CheckBox runat="server" />
</cc1:TabPanel>

In this case, I wouldn’t want the checkbox to be there. How can I block this from happening?

Answer 1

I figured it out.

Had to throw an exception under AddedControl procedure that I overrided from the WebControl if the type of the control being added was not of the type I wanted.

Now the designer shows a beautiful red error-message on the control itself, preventing me from doing such a foolish thing.

Awesome!