ASP.NET How to access a deeply nested user control on the parent page

Question

I have a login control and at is nested 2 deep in a header control i.e Page --> Header Control --> Login Control. I cannot get a reference to the control on the page using FindControl. I want to be able to set the visible property of the control like

  if (_loginControl != null)
            _loginControl.Visible = false;

I ended up using a recursive FindControl method to find the nested control.

    public static Control FindControlRecursive(Control root, string id)
    {
        if (root.ID == id)
        {
            return root;
        }

        foreach (Control c in root.Controls)
        {
            Control t = FindControlRecursive(c, id);
            if (t != null)
            {
                return t;
            }
        }

        return null;
    }

Answer 1

A good way would be to use:

Page.FindControl() 

if that yields null, the control is not there.

Answer 2

Try calling this.FindControl("_loginControl") or this.Page.FindControl("_loginControl").

See MSDN for method details: http://msdn.microsoft.com/en-us/library/system.web.ui.control.findcontrol.aspx

Answer 3

Are you needing to disable/hide the User Control from the ASP.NET page it resides on (or does the User Control exist on a master page, say)? If it's in the same page, then in your ASP.NET page's code-behind you'd do:

MyUserControlsID.Visible = false

Where MyUserControl is the ID of your User Control. To determine the ID of your User Control look at the markup of your .aspx page and you will see something like this:

<uc1:UserControlName ID="MyUserControlsID" runat="server" ... />

Happy Programming!

Answer 4

The login control, if it's registered in the markup, will also be an instance member of your codebehind page; you can refer to it from the codebehind class as if it were a normal member, using the same name you provided as the ID (I do recommend using codebehinds for most logic, instead of inlining code in the markup, BTW).

You can also use the FindControl() method of your page, which will search its control subtree for a control with a given ID. That takes longer, so I would recommend the first option unless the logic control is added dynamically and you don't always know it's there.