Get list of users with assigned roles in asp.net identity 2.0

Question

I have a drop down list box which lists roles. I want to get the list of users having that role. I mean list of users that are in "Administrator" role or "CanEdit" role. Here is my code:

public IQueryable<Microsoft.AspNet.Identity.EntityFramework.IdentityUser> 
  GetRolesToUsers([Control] string ddlRole)
{    
  //ddlRole returns role Id, based on this Id I want to list users

  var _db = new ApplicationDbContext();
  IQueryable<Microsoft.AspNet.Identity.EntityFramework.IdentityUser> query = _db.Users;

  if (ddlRole != null)
  {
    //query = query.Where(e => e.Claims == ddlRole.Value);  ???????              
  }

  return query;
}

Please help.

Updated Code (still error)

public List<IdentityUserRole> GetRolesToUsers([Control]string ddlRole)
{

  var roleManager = 
   new RoleManager<IdentityRole>(new RoleStore<IdentityRole>(new ApplicationDbContext()));
  var users = roleManager.FindByName("Administrator").Users.ToList();
  return users;
}

Error: The Select Method must return one of "IQueryable" or "IEnumerable" or "Microsoft.AspNet.Identity.EntityFramework.IdentityUser" when ItemType is set to "Microsoft.AspNet.Identity.EntityFramework.IdentityUser".

I tried various castings but none of them helped.

UPDATE (working solution)

Thanks to chris544, his idea helped me to fix this. Here is working method:-

public List<ApplicationUser> GetRolesToUsers([Control]string ddlRole)
{
  var context = new ApplicationDbContext();
  var users =
    context.Users.Where(x => x.Roles.Select(y => y.RoleId).Contains(ddlRole)).ToList();

  return users;
}

Answer 1

Not an expert, but ...

There seemed to be no built in funcionality for this in Identity and I could not get it work from built in Roles also (it seems to not work with claims based Identity).

So I ended up doing something like this:

var users = context.Users        
    .Where(x => x.Roles.Select(y => y.Id).Contains(roleId))
    .ToList();

• x.Roles.Select(y => y.Id) gets a list of all role ids for user x
• .Contains(roleId) checks if this list of ids contains necessary roleId