Nested Master Pages change programmatically

I have a PAGE with a structure like this:

PAGE = MASTER PAGE A + nested MASTER PAGE B of A

MASTER PAGE A:

-----------
Header
-----------
BODY
-----------
Footer
-----------

MASTER PAGE B:

BODY-------------------------------
          |         |             |  
ColumLeft | Content | ColumRight  |
          |         |             |
-----------------------------------

One of the features I need to develop is to be able to chang开发者_JAVA百科e the nested MASTER PAGE programmatically. For example changing MASTER PAGE B with C (containing a different layout like just 2 columns) maintaining the Header and Footer centralized.

At the moment on PAGE I use this code to select another MP, but I am not able to do it because seems when selecting a new nested page asp.net loose the reference to the main MASTER PAGE A.

void Page_PreInit(Object sender, EventArgs e)
{
    this.MasterPageFile = "~/NewMaster.master";
}

Questions:

• Any idea how to solve it?
• Would be better have only a Master Page (1 Level) and include the Header and Footer with another tecnic? If yes what would you suggest me?

In order to change the MasterPage programmatically you have to specify its type right after the page registration link in the xml/html page.

<%@ Page Language="C#" 
    MasterPageFile="~/MasterPage.master" 
    AutoEventWireup="false" 
    CodeFile="MyCodeFile.aspx.cs" 
    Inherits="MyCodeFile"
    title="Untitled Page" %>
<%@ MasterType 
    virtualpath="~/MasterPage.master" 
%>

I don't recommend using this architecture to achieve what you want to achieve, but this is how you would do it.

In this case I wouldn't use nested masterpages, but just one masterpage. For the columns I would use RenderPartial or RenderAction. It's not as DRY as you would wish, because you need to add RenderPartial("LeftColumn") in every view, so I understand your problem, but this is the way I do it.

NB: RenderAction is availbale in MVC. For an article about it see e.g.: http://haacked.com/archive/2009/11/18/aspnetmvc2-render-action.aspx