实体框架HierarchyId的解决方法(Entity Framework HierarchyId

EF 5.0

我工作的一个原型一起测试HIERARCHYID和实体框架。 我有以下模式：

Create Table dbo.Employee
(
   EmployeeId int identity not null,
   Name nvarchar(100) not null,
   Node hierarchyid not null,
   NodePath as Node.ToString() persisted,
   Level AS Node.GetLevel() persisted,
   ManagerNode as Node.GetAncestor(1) persisted,
   ManagerNodePath as Node.GetAncestor(1).ToString() persisted
);

Alter Table dbo.Employee
    Add Constraint EmployeePK Primary Key NonClustered (EmployeeId);

Go

--Enforce Hierarchy
Alter Table dbo.Employee
    Add Constraint EmployeeManagerNodeNodeFK Foreign Key (ManagerNode) References Employee(Node);
Go

Create Unique Clustered Index EmployeeDepthFirstIndex on dbo.Employee(Node);

Go

Create NonClustered Index EmployeeBreathFirstIndex on dbo.Employee(Level, Node);

Go

从我的阅读，HIERARCHYID数据类型目前不支持EF的，但也有一些建议的解决方法，比如创建计算列（Node.ToString（）），我在上面所做的。

有没有一种方法来设置EF以便它能够识别的父/子关系，所以我可以有效地拥有下属集？ 例如

Employee.Subordinates

我能想到的唯一的事情就是创建一个经理ID列瓦特/ FK，但后来我有效地存储层次结构在两个地方。

谢谢你的帮助！

Answer 1:

EF6现在是开源的，所以很容易添加HierarcyID支持。 我加入了这一点。 您也可以下载体改源和遵守/签订CodePlex从dll文件： http://entityframework.codeplex.com/SourceControl/network/forks/zgabi/efhierarchyidrc1 （有时叉名称更改），或者从的NuGet： https：//开头WWW .nu​​get.org /包/ EntityFrameworkWithHierarchyId / Currenty EF6是RC1的状态，但我会合并修改EF6的每一个更高版本。

我有以下型号：

public class Employee
{
    public int EmployeeId { get; set; }
    [Required, MaxLength(100)]
    public string Name { get; set; }
    [Required]
    public HierarchyId Node { get; set; }

    public IQueryable<Employee> GetSubordinates(MyContext context)
    {
        return context.Employees.Where(o => Node == o.Node.GetAncestor(1));
    }
}

public class MyContextInitializer : CreateDatabaseIfNotExists<MyContext>
{
    protected override void Seed(MyContext context)
    {
        context.Database.ExecuteSqlCommand(
            "ALTER TABLE [dbo].[Employees] ADD [ManagerNode] AS ([Node].[GetAncestor]((1))) 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/") });
    }
}

public class MyContext : DbContext
{
    public DbSet<Employee> Employees { get; set; }
}

生成的数据库：

CREATE TABLE [dbo].[Employees](
    [EmployeeId] [int] IDENTITY(1,1) NOT NULL,
    [Name] [nvarchar](100) NOT NULL,
    [Node] [hierarchyid] NOT NULL,
    [ManagerNode]  AS ([Node].[GetAncestor]((1))) PERSISTED,
 CONSTRAINT [PK_dbo.Employees] PRIMARY KEY CLUSTERED 
(
    [EmployeeId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],
 CONSTRAINT [UK_EmployeeNode] UNIQUE NONCLUSTERED 
(
    [Node] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

ALTER TABLE [dbo].[Employees]  WITH CHECK ADD  CONSTRAINT [EmployeeManagerNodeNodeFK] FOREIGN KEY([ManagerNode])
REFERENCES [dbo].[Employees] ([Node])

例如让员工EMP1的子节点：

    using (var c = new MyContext())
    {
        var firstItem = c.Employees.Single(o => o.Node == new HierarchyId("/1/"));

        foreach (var table1 in firstItem.GetSubordinates(c))
        {
            Console.WriteLine(table1.EmployeeId + " " + table1.Name);
        }
    }

结果：

4 Emp3
7 Emp6

Answer 2:

用VARBINARY（892），而不是HIERARCHYID。 EF承认VARBINARY返回字节数组。 您可以字节数组转换为SqlHierarchyid类型和使用hyrarchy荚功能。 有了这个解决办法，你甚至可以在其他数据库使用HIERARCHYID功能。 见http://www.casavillar.com.br/blog更多的细节和链接块并github上，你会发现样本包括MySQL

文章来源: Entity Framework HierarchyId Workarounds