Registering custom / user controls problem

Hi,

I have a WebUserControl, let's call it "BaseControl.ascx" that acts as a base control for a custom control (a class that inherits BaseControl). Inside BaseControl I have a couple of regular controls (for example a DropDownList called 'dropdown'), which I try to populate in the inheriting control:

csharp Code:

namespace ProjectName.Controls
{
    public class SpecializedControl : BaseControl
    {
        public void SetupList()
        {
            dropdown.DataSource = "ABCDEFG".ToCharArray();
            dropdown.DataBind();
        }
    }
}

As far as I know, the only way to register a custom control (eg, not a .ascx control but a class inheriting a control) is to use this syntax on the page:

Code:

---

<%@ Register Assembly="ProjectName" Namespace="ProjectName.Controls" TagPrefix="custom" %>

---

This seems to work, I can place a SpecializedControl on the page with this:

Code:

---

<custom:SpecializedControl runat="server" ID="test" />

---

However, when I now call the 'SetupList' method on this control, from the Page_Load event, it seems that 'dropdown' (the DropDownList control in BaseControl.ascx) is null, it seems it is never instantiated.


To test what is happening I just created a simple TestControl.ascx (note: an ascx file again, so a WebUserControl and not a custom control), also with a dropdown and the same SetupList method.

When I register this control using the following syntax, everything works fine:

Code:

---

<%@ Register Src="~/Controls/TestControl.ascx" TagName="TestControl" TagPrefix="custom" %>

---

I can call SetupList and the list is populated just fine.

When I register the exact same control however with the other syntax, it does not work, and 'dropdown' is null:

Code:

---

<%@ Register Assembly="ProjectName" Namespace="ProjectName.Controls" TagPrefix="custom" %>

---

In this test case I can choose which syntax to use, but in my actual case I can't. The control I want to put on my page is not an ascx file, it's a class that inherits another control (a custom control), so as far as I know I am stuck with this second syntax. So, I cannot get this to work...

I also tried creating the control dynamically using LoadControl, but that gives the same problem.


Long story short: it seems like I have to use the first syntax to register a control (with a 'Src' tag pointing to the control ascx file), but I can't since there is no ascx file...

How can I do this properly?

Can't say that i have tried the double custom that you do but have you tried adding it to web.config directly?
Also have a look here:
http://haacked.com/archive/2006/11/1...eb.config.aspx

http://weblogs.asp.net/scottgu/archi...eb-config.aspx

Hello,

The only thing that I can think is that by inheriting from BaseControl, the instantiation of the controls within that UserControl is not happening.

You could try using Page.LoadControl:

http://msdn.microsoft.com/en-us/libr...adcontrol.aspx

To load the BaseControl dynamically, when your control requires it, but this seems a little "messy".

Is there a reason why you are mixing Custom Controls and UserControls? Why not simply have BaseControl as a Control in it's own right, i.e. don't use an ascx at all?

Gary

sapator: tried that, didn't work, same result.

Gep: also tried LoadControl, same result again.

It seems to be impossible :(

The reason I want it like this is because BaseControl is a generic control. It represents a filter on a particular type. It has a dropdown (amongst other controls) that shows a list of possible values for the generic type, and handles all the filtering on the selected value internally (a method that accepts a list of items and returns those that match the selected item ). Then I have one class inheriting BaseControl for each type.

The generics are not the problem by the way, tried it without genetics too and same result.

I let this idea go and just pit all the filtering code on the page itself. A lot more and repeated code but it works...

Hey,

I get what you are trying to do, but why not add the logic, and controls in an actual control (i.e. render everything in code) rather than using a composite control. Dynamically render out the DropDownList, rather than placing it in an ASCX.

Gary

Hmmm that might work... I'll try that.

Quote:

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Originally Posted by NickThissen

Hmmm that might work... I'll try that.

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Fingers crossed :) Let me know how you get on.

Gary