public void UpdateToDoItem(Guid listId, ToDoItemDTO item, string owner)
{
ToDoList toDoList = GetToDoList(listId, owner);
if (toDoList == null)
{
throw new EntityNotFoundException();
}
else if (toDoList.Owner != owner)
{
throw new UnauthorizedException();
}
ToDoItem oldItem = toDoList.Items.SingleOrDefault(i => i.Id.Equals(item.Id));
if (oldItem == null)
{
throw new EntityNotFoundException();
}
oldItem.Update(item.ToEntity(toDoList));
_context.SaveChanges();
}