public IQueryable <TimePeriod> GetMyTimePeriods(IPrincipal User)
{
ApplicationUser currentUser = GetUser(User.Identity);
if (currentUser == null)
{
return(Enumerable.Empty <TimePeriod>().AsQueryable());
}
return(TimePeriods.Where(tp => tp.Activity.Task.Project.User.Id == currentUser.Id));
}