How to filter ICollection<ApplicationUser> on a Role in ASP.NET MVC 5's Identity

Question

I have added 3 roles:

1. Administrators
2. Staff
3. Registered

Now I want to display a list of all Registered users. I'm afraid I'm not getting the Identity system, because I am trying to do something like this:

Spoiler Alert: not working code

var listOfNames = _unitOfWork.UserRepository.All()
                                            .Where(u => u.Roles.Contains("Registered"))
                                            .ToList();

This obviously does not work, so I went searching for an answer. Unfortunately I did not get any. The closest I could find was a post by Scott Allen who mentioned IUserRoleStore which has the following implementations:

• Add a user to a role
• Get all the roles for a user
• Check is a user is in a specific role
• Remove a user from a role

But still, not getting it :/

I have also tried the methods in this Question, but Roles.Select(r => r.Name).Contains("client") does not work because the Name property can't be found?

How can I get this list of ApplicationUser objects?

Update

---

Sean's answer helped me to dig a little deeper. I'm not sure this is the best way, but it works for my needs.

var users = context.Users;
var roleUsers = context.Roles.Single(one => one.Name == "Registered").Users;

names = (from r in roleUsers
join u in users on r.UserId equals u.Id
select u.UserName).ToList();

If this is inefficient, I'd love to hear why and how I can improve it.

Answer 1

Assuming AspNetIdentity2.0...I see you are using a repository pattern so in there, could you use the RoleManager:

var users = RoleManager.Roles.Single(x => x.Name == "Registered").Users;

Unfortunately (and misleadingly) this returns a list of UserRoles but at least you've got the users' UserIds, and from there, can fetch the Users.