Can content page use ContentPlaceHolderID of master parent of its master page (nested master pages)

Question

I have a 3 level nested master pages and a content page. parent1 is the top parent, parent2 is parent of parent3 and parent3 is the parent of the content page.

I get an error 'Cannot find ContentPlaceHolder xxx...' where xxx is a ContentPlaceholder. It resides in parent2 and content page is trying to fill it.

Can content pages only use their direct parent ContentPlaceHolders or can they also use any of the higher master pages?

Answer 1

I believe content pages can only use the ContentPlaceHolder of the direct parent.

Answer 2

Getting the Values of Controls on the Master Page At run time, the master page is merged with the content page, so the controls on the master page are accessible to content page code. (If the master page contains controls in a ContentPlaceHolder control, those controls are not accessible if overridden by a Content control from the content page.) The controls are not directly accessible as master-page members because they are protected. However, you can use the FindControl method to locate specific controls on the master page. If the control that you want to access is inside a ContentPlaceHolder control on the master page, you must first get a reference to the ContentPlaceHolder control, and then call its FindControl method to get a reference to the control.

The following example shows how you can get a reference to controls on the master page. One of the controls being referenced is in a ContentPlaceHolder control and the other is not.

Visual Basic Copy Code ' Gets a reference to a TextBox control inside a ContentPlaceHolder

Dim mpContentPlaceHolder As ContentPlaceHolder
Dim mpTextBox As TextBox
mpContentPlaceHolder = _
    CType(Master.FindControl("ContentPlaceHolder1"), _
    ContentPlaceHolder)
If Not mpContentPlaceHolder Is Nothing Then
    mpTextBox = CType(mpContentPlaceHolder.FindControl("TextBox1"), _
        TextBox)
    If Not mpTextBox Is Nothing Then
        mpTextBox.Text = "TextBox found!"
    End If

Since you want to Find a nested Content place holder you may have to find the parent then use that instance to find the child