[C#.NET][Entity Framework] 在 Code First 實作具有排序功能的 Guid

2014-07-15

4991
0
Entity Framework 6
2015-12-28

POCO Proxy 定義，用 Id 產生具有順序的流水號，用來驗証 Guid 是否能照順序排序：


{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [Key]
    public Guid Guid { get; set; }

    public string Name { get; set; }
}

DbContex 實作如下：


{
    public DbSet<Employee> Employees { get; set; }

    public UserDbContext(string contectString)
        : base(contectString)
    {
    }

    public UserDbContext()
        : base("localdb")
    {
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        Database.SetInitializer(new MyDropCreateDatabaseAlways());
    }
}

建立假資料：


{
    protected override void Seed(UserDbContext context)
    {
        base.Seed(context);
        context.Employees.Add(new Employee() { Guid = Guid.NewGuid(), Name = "jordan" });
        context.Employees.Add(new Employee() { Guid = Guid.NewGuid(), Name = "kobe" });
        context.Employees.Add(new Employee() { Guid = Guid.NewGuid(), Name = "pippen" });
        context.Employees.Add(new Employee() { Guid = Guid.NewGuid(), Name = "bibby" });
        context.Employees.Add(new Employee() { Guid = Guid.NewGuid(), Name = "omer" });
        context.Employees.Add(new Employee() { Guid = Guid.NewGuid(), Name = "rose" });
        context.Employees.Add(new Employee() { Guid = Guid.NewGuid(), Name = "wade" });
        context.Employees.Add(new Employee() { Guid = Guid.NewGuid(), Name = "lin" });
    }
}

使用 LINQPad 來觀察，操作步驟請參考

http://www.dotblogs.com.tw/yc421206/archive/2014/07/15/145969.aspx

來段小代碼，看看是否有排序功能，我對 Guid 欄位排序，Id 欄位沒有按照順序排列，表示該 Guid 沒有順序性