// PUT api/TodoList/5
        public async Task<IHttpActionResult> PutTodoList(int id, TodoList todolist)
        {
            if (!ModelState.IsValid)
            {
                return this.BadRequest(this.ModelState);
            }

            if (id != todolist.TodoListId)
            {
                return this.BadRequest();
            }

            this.db.Entry(todolist).State = EntityState.Modified;

            try
            {
                await this.db.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!this.TodoListExists(id))
                {
                    return this.NotFound();
                }
                else
                {
                    throw;
                }
            }

            return this.StatusCode(HttpStatusCode.NoContent);
        }
        public async Task<IHttpActionResult> PostTodoList(TodoList todolist)
        {
            if (!ModelState.IsValid)
            {
                return this.BadRequest(this.ModelState);
            }

            todolist.UserId = User.Identity.Name;
            this.db.TodoLists.Add(todolist);
            await this.db.SaveChangesAsync();

            return this.CreatedAtRoute("DefaultApi", new { id = todolist.TodoListId }, todolist);
        }
        /// <summary>
        /// Initiate a new todo list for new user
        /// </summary>
        /// <param name="userName"></param>
        private static void InitiateDatabaseForNewUser(string userName)
        {
            TodoItemContext db = new TodoItemContext();
            TodoList todoList = new TodoList();
            todoList.UserId = userName;
            todoList.Title = "My Todo List #1";
            todoList.Todos = new List<TodoItem>();
            db.TodoLists.Add(todoList);
            db.SaveChanges();

            todoList.Todos.Add(new TodoItem() { Title = "Todo item #1", TodoListId = todoList.TodoListId, IsDone = false });
            todoList.Todos.Add(new TodoItem() { Title = "Todo item #2", TodoListId = todoList.TodoListId, IsDone = false });
            db.SaveChanges();
        }