How to display master pages dynamically based on user

Question

Hi,
I have three roles engineer,supuvisor and manager for my website
and I have three master pages engineer.master , supervisor.master and mgr.master
and i have some specific aspx pages for engineer,supervisor and manager.
I want to use engineer.master page for an aspx page if engineer user is logged in and want to use supervisor.master page if supervisor logged in ans so on for the manager.
How can I achieve this?
Thanks in advance!!!
Im getting error
here is the code :
protected override void OnPreInit(EventArgs e) {
base.OnPreInit(e);
switch (Session["role"].ToString())
{
case "1":
MasterPageFile = "ME.Master";
break;
case "2":
MasterPageFile= "Supervisor.Master";
break;
case "3":
MasterPageFile = "Manager.Master";
break;
default:
MasterPageFile = "default.Master";
break;
}
Thank you

Mukesh Kumar · Answer

Hi ,
Try this,
void Page_PreInit(Object sender, EventArgs e) {
MembershipUser user = Membership.GetUser(Login1.UserName);     if(Roles.IsUserInRole(user.UserName,"Engineer"))     {             this.MasterPageFile = "Engineer.master";     }     else if(Roles.IsUserInRole(user.UserName,"Supervisor"))
{             this.MasterPageFile = "Supervisor.Master";     }     else if(Roles.IsUserInRole(user.UserName,"Manager"))
{             this.MasterPageFile = "Manager.Master";     }     else     {         this.MasterPageFile ="Default.Master"     } }

shshva · Answer

Exception Details: System.Web.HttpException: The file '/Manager.Master' does not exist.

shshva · Answer

i still couldn't find the solution :-(.. whenever i logon use supervisor id its directed to Engineer master page. please advice.