How to get users not in role,

Question

Is there any reasonably efficient way to get a list of users who are not in a specific role?

The only methods I can see are

1. Get all the users from DB and do a check in code

2. Go directly to the db and sidestep the role provider

Answer 1

Another way is to extend RoleProvider with the method GetUsersNotInRole() and query the DB there. You can also combine RoleProvider.GetUsersInRole() with MembershipProvider.GetAllUsers() and find the difference

Answer 2

You could just get the all user list and extract users in role specified from the list:

var usersInRole = Roles.GetUsersInRole("admin");
var users = Membership.GetAllUsers()
    .Cast<MembershipUser>()
    .Select(u => 
        !usersInRole.Contains(u.UserName)
    );

Answer 3

Changing the Select to Where in the code provided by Alex will actually return the results instead of just true/false.

var usersInRole = Roles.GetUsersInRole("admin");
var users = Membership.GetAllUsers()
    .Cast<MembershipUser>()
    .Where(u => 
        !usersInRole.Contains(u.UserName)
    );

Answer 4

I don't think that there is anything wrong with by-passing the role provider and querying the database directly. You will definitely get the best performance this way.