How to write AuthorizeAttribute if the role contains space

Create your own attribute and get from AuthorizeAttribute. Then override the AuthorizeCore method and implement your own logic, checking for a role that contains a space.

An example might be something like this:

public class CustomAuthAttribute : AuthorizeAttribute
{
   private readonly IUserRoleService _userRoleService;
   private string[] _allowedRoles;

   public CustomAuthAttribute(params string[] roles)
   {
      _userRoleService = new UserRoleService();
      _allowedRoles = roles;
   }
   protected override bool AuthorizeCore(HttpContextBase httpContext)
   {
    //something like this.
    var userName = httpContext.User.Identity.Name;
    var userRoles = _userRoleService .GetUserRoles(userName); // return list of strings
    return _allowedRoles.Any(x => userRoles.Contains(x));
   }

}

Using

[CustomAuth("role withspace","admin")]
public ActionResult Index()
{
}