asp.net FindControl Recursively

Question

This is a really weird one - I will do my best to explain.

I have a basic master page:

<%@ Master Language=\"VB\" CodeFile=\"MasterPage.master.vb\         


        

Answer 1

Why don't you simply expose properties that return PH1 and PH2, because the master has the reference of them and you don't need to iterate all child controls of master:

Public ReadOnly Property Container1 As PlaceHolder
    Get
        Return Me.PH1
    End Get
End Property

Public ReadOnly Property Container2 As PlaceHolder
    Get
        Return Me.PH2
    End Get
End Property

You can access them:

Dim ph1 As PlaceHolder = DirectCast(Me.Master, myMaster).Container1
Dim ph2 As PlaceHolder = DirectCast(Me.Master, myMaster).Container2

Another problem is this line:

controlInstance1.ID = "control_2"

You are setting only controlInstance1's ID twice, but that doesn't cause your issue.

Your main problem is that you are adding the controls to the placeholders in Page_Init instead of Page_Load. Therefore the UserControls can't load their ViewState and the ListView is empty. Recreate them in Page_Load and it will work.

Edit: But i must admit that i don't know why your iterate extension wins over the recursive. The reference on the placeholders are the same, they shouldn't work both, weird.

summary:

• it works with my properties,
• putting all in page's load event handler instead init
• with your iterate-extension(for whatever reasons)

It also works if you add both UserControls at last, after you've found the placeholders via FindControlRecursively.

zone.Controls.Add(controlInstance1)
zone2.Controls.Add(controlInstance2)

I'm losing motivation on this, but i'm sure you'll find the answer here. Controls.Add loads it's parent's ViewState into all childs and therefore it depends on when you add the controls, also the index of the controls in their parent controls must be the same on postback to reload the ViewState.

Your recursive extension method touches control1's ID after you've added it to PH1(while searching PH2), the iterative extension does not. I assume that this corrupts it's ViewState in Page_Init.

Conclusion Use properties instead