‫کار با نوع داده‌ی HierarchyID توسط Entity framework

 PM> install-package EntityFrameworkWithHierarchyId

public class Employee
{    public int Id { get; set; }    [Required, MaxLength(100)]    public string Name { get; set; }    [Required]    public HierarchyId Node { get; set; } // نوع داده جدید
}

public class MyContext : DbContext
{    public DbSet<Employee> Employees { get; set; }    public MyContext()        : base("Connection1")    {        this.Database.Log = log => Console.WriteLine(log);    }
}
public class Configuration : DbMigrationsConfiguration<MyContext>
{    public Configuration()    {        AutomaticMigrationsEnabled = true;        AutomaticMigrationDataLossAllowed = true;    }    protected override void Seed(MyContext context)    {        if (context.Employees.Any())            return;        context.Database.ExecuteSqlCommand(            "ALTER TABLE [dbo].[Employees] ADD NodePath as Node.ToString() persisted");        context.Database.ExecuteSqlCommand(            "ALTER TABLE [dbo].[Employees] ADD Level AS Node.GetLevel() persisted");        context.Database.ExecuteSqlCommand(            "ALTER TABLE [dbo].[Employees] ADD ManagerNode as Node.GetAncestor(1) persisted");        context.Database.ExecuteSqlCommand(            "ALTER TABLE [dbo].[Employees] ADD ManagerNodePath as Node.GetAncestor(1).ToString() persisted");        context.Database.ExecuteSqlCommand(            "ALTER TABLE [dbo].[Employees] ADD CONSTRAINT [UK_EmployeeNode] UNIQUE NONCLUSTERED (Node)");        context.Database.ExecuteSqlCommand(            "ALTER TABLE [dbo].[Employees]  WITH CHECK ADD CONSTRAINT [EmployeeManagerNodeNodeFK] " +            "FOREIGN KEY([ManagerNode]) REFERENCES [dbo].[Employees] ([Node])");        context.Employees.Add(new Employee { Name = "Root", Node = new HierarchyId("/") });        context.Employees.Add(new Employee { Name = "Emp1", Node = new HierarchyId("/1/") });        context.Employees.Add(new Employee { Name = "Emp2", Node = new HierarchyId("/2/") });        context.Employees.Add(new Employee { Name = "Emp3", Node = new HierarchyId("/1/1/") });        context.Employees.Add(new Employee { Name = "Emp4", Node = new HierarchyId("/1/1/1/") });        context.Employees.Add(new Employee { Name = "Emp5", Node = new HierarchyId("/2/1/") });        context.Employees.Add(new Employee { Name = "Emp6", Node = new HierarchyId("/1/2/") });        base.Seed(context);    }
}

using (var context = new MyContext())
{    Console.WriteLine("\ngetItems OrderByDescending(employee => employee.Node)");    var employees = context.Employees.OrderByDescending(employee => employee.Node).ToList();    foreach (var employee in employees)    {        Console.WriteLine("{0} {1}", employee.Id, employee.Node);    }
 }

SELECT
    [Extent1].[Id] AS [Id],
    [Extent1].[Name] AS [Name],
    [Extent1].[Node] AS [Node]
    FROM [dbo].[Employees] AS [Extent1]
    ORDER BY [Extent1].[Node] DESC


6 /2/1/
3 /2/
7 /1/2/
5 /1/1/1/
4 /1/1/
2 /1/
1 /

using (var context = new MyContext())
{    Console.WriteLine("\nGetAncestor(1) of /1/");    var firstItem = context.Employees.Single(employee => employee.Node == new HierarchyId("/1/"));    foreach (var item in context.Employees.Where(employee => firstItem.Node == employee.Node.GetAncestor(1)))    {        Console.WriteLine("{0} {1}", item.Id, item.Name);    }
}

SELECT TOP (2)
    [Extent1].[Id] AS [Id],
    [Extent1].[Name] AS [Name],
    [Extent1].[Node] AS [Node]
    FROM [dbo].[Employees] AS [Extent1]
    WHERE cast('/1/' as hierarchyid) = [Extent1].[Node]

SELECT
    [Extent1].[Id] AS [Id],
    [Extent1].[Name] AS [Name],
    [Extent1].[Node] AS [Node]
    FROM [dbo].[Employees] AS [Extent1]
    WHERE (@p__linq__0 = ([Extent1].[Node].GetAncestor(1))) OR ((@p__linq__0 IS
NULL) AND ([Extent1].[Node].GetAncestor(1) IS NULL))
-- p__linq__0: '/1/' (Type = Object)

4 Emp3
7 Emp6

var list = context.Employees.Where(
          employee => employee.Node.IsDescendantOf(new HierarchyId("/1/")) &&
                              employee.Node.GetLevel() == 2).ToList();

SELECT
    [Extent1].[Id] AS [Id],
    [Extent1].[Name] AS [Name],
    [Extent1].[Node] AS [Node]
    FROM [dbo].[Employees] AS [Extent1]
    WHERE (([Extent1].[Node].IsDescendantOf(cast('/1/' as hierarchyid))) = 1) 
    AND (2 = ([Extent1].[Node].GetLevel()))

var items = context.Employees.Where(employee => employee.Node.IsDescendantOf(new HierarchyId("/1/")))    .Select(employee => new    {        Id = employee.Id,        OrigPath = employee.Node,        ReparentedValue = employee.Node.GetReparentedValue(new HierarchyId("/1/"), HierarchyId.GetRoot()),        Level = employee.Node.GetLevel()    }).ToList();
foreach (var item in items)
{    Console.WriteLine("Id:{0}; OrigPath:{1}; ReparentedValue:{2}; Level:{3}", item.Id, item.OrigPath, item.ReparentedValue, item.Level);
}

SELECT
    [Extent1].[Id] AS [Id],
    [Extent1].[Node] AS [Node],
    [Extent1].[Node].GetReparentedValue(cast('/1/' as hierarchyid), hierarchyid::GetRoot()) AS [C1],
    [Extent1].[Node].GetLevel() AS [C2]
    FROM [dbo].[Employees] AS [Extent1]
    WHERE ([Extent1].[Node].IsDescendantOf(cast('/1/' as hierarchyid))) = 1


Id:2; OrigPath:/1/; ReparentedValue:/; Level:1
Id:4; OrigPath:/1/1/; ReparentedValue:/1/; Level:2
Id:5; OrigPath:/1/1/1/; ReparentedValue:/1/1/; Level:3
Id:7; OrigPath:/1/2/; ReparentedValue:/2/; Level:2