public IList<Category> Categories { get; set; }
        PRotected void Page_Load(object sender, EventArgs e)
        {

//這是靜態給categories賦值，怎么動態賦值呢，就是連接數據庫后查詢數據綁定categories，使他的數據成下面一樣顯示
            Categories = new List<Category>
            {
                new Category
                {
                    Name = "category 1",
                    Children = new List<Category>
                    {
                        new Category
                        {
                            Name="category 1-1",
                            Children = new List<Category>{}
                        },
                        new Category
                        {
                            Name="category 1-2",
                            Children = new List<Category>{}
                        },
                    }
                },
                new Category{
                    Name ="category 2",
                    Children = new List<Category>{
                        new Category{
                            Name = "category 2-1",
                            Children = new List<Category>{}
                        },
                        new Category
                        {
                            Name = "category 2-2",
                            Children = new List<Category>{}
                        }
                    }
                }
            };
        }