Question

为什么删除子项（员工）时删除了父项（商店）？

我使用约定Cascade.All 进行配置。

用户输入序列非常简单：

从空数据库开始

添加父级

保存，加载（加载=重新加载完整对象图）

添加孩子

保存，加载

删除儿童

结果：清空数据库。（家长删除）

这可能是一个基本的映射错误，因为这是我第一次接受NHibernate。我希望商店成为聚合根，并认为通过不在Store.Staff属性上设置Inverse，然后Store表将负责保存，因此聚合根。那是一种误解吗？实际上如果我使用Inverse，我仍然会得到相同的结果。也许吧这不是问题，但我也想理解这一点。

并且故意不使用更广泛的会话范围，因为我想学习如何使用分离和瞬态实体。

员工删除方法：

class EmployeeRepository public static void Delete(Employee employee) { using (ISession session = FNH_Manager.OpenSession()) { using (ITransaction transaction = session.BeginTransaction()) { if (employee.Id != 0) { var emp = session.Get(typeof(Employee), employee.Id); if (emp != null) { session.Delete(emp); transaction.Commit(); } } } } }

映射

public class StoreMap : ClassMap<Store> { public StoreMap() { Id(x => x.Id); Map(x => x.Name); HasMany(x => x.Staff) // 1:m .Inverse() // tried both with and without, what is correct? .Cascade.All(); HasManyToMany(x => x.Products) // m:m .Cascade.All() .Table("StoreProduct"); } } public class EmployeeMap : ClassMap<Employee> { public EmployeeMap() { Id(x => x.Id); // By default an int Id is generated as identity Map(x => x.FirstName); Map(x => x.LastName); References(x => x.Store); // m:1 } } public class ProductMap : ClassMap<Product> { public ProductMap() { Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.Name).Length(20); Map(x => x.Price).CustomSqlType("decimal").Precision(9).Scale(2); HasManyToMany(x => x.StoresStockedIn) .Cascade.All() .Inverse() .Table("StoreProduct"); } }

实体：

public class Store { public int Id { get; private set; } public string Name { get; set; } public IList<Product> Products { get; set; } public IList<Employee> Staff { get; set; } public Store() { Products = new List<Product>(); Staff = new List<Employee>(); } // AddProduct & AddEmployee is required. "NH needs you to set both sides before // it will save correctly" ?? public void AddProduct(Product product) { product.StoresStockedIn.Add(this); Products.Add(product); } public void AddEmployee(Employee employee) { employee.Store = this; Staff.Add(employee); } } public class Employee { public int Id { get; private set; } public string FirstName { get; set; } public string LastName { get; set; } public Store Store { get; set; } }

编写伪代码并生成“SQL”：

程序启动

加载：存储stores = StoreRepository.GetAll（）

NHibernate: SELECT this_.Id as Id3_0_, this_.Name as Name3_0_ FROM [Store] this_

添加父级：将商店添加到空集合商店

保存：StoreRepository.SaveOrUpdate（存储）

NHibernate: SELECT store0_.Id as Id3_0_, store0_.Name as Name3_0_ FROM [Store] store0_ WHERE store0_.Id=@p0;@p0 = 0 [Type: Int32 (0)] NHibernate: INSERT INTO [Store] (Name) VALUES (@p0); select SCOPE_IDENTITY();@p0 = NULL [Type: String (4000)]

加载：stores = StoreRepository.GetAll（）

NHibernate: SELECT this_.Id as Id3_0_, this_.Name as Name3_0_ FROM [Store] this_ NHibernate: SELECT products0_.Store_id as Store2_1_, products0_.Product_id as Product1_1_, product1_.Id as Id1_0_, product1_.Name as Name1_0_, product1_.Price as Price1_0_ FROM StoreProduct products0_ left outer join [Product] product1_ on products0_.Product_id=product1_.Id WHERE products0_.Store_id=@p0;@p0 = 16 [Type: Int32 (0)] NHibernate: SELECT staff0_.Store_id as Store4_1_, staff0_.Id as Id1_, staff0_.Id as Id0_0_, staff0_.FirstName as FirstName0_0_, staff0_.LastName as LastName0_0_, staff0_.Store_id as Store4_0_0_ FROM [Employee] staff0_ WHERE staff0_.Store_id=@p0;@p0 = 16 [Type: Int32 (0)]

为所选商店添加子项：空子项集合

保存：StoreRepository.SaveOrUpdate（存储）

NHibernate: SELECT store0_.Id as Id3_0_, store0_.Name as Name3_0_ FROM [Store] store0_ WHERE store0_.Id=@p0;@p0 = 16 [Type: Int32 (0)] NHibernate: SELECT products0_.Store_id as Store2_1_, products0_.Product_id as Product1_1_, product1_.Id as Id1_0_, product1_.Name as Name1_0_, product1_.Price as Price1_0_ FROM StoreProduct products0_ left outer join [Product] product1_ on products0_.Product_id=product1_.Id WHERE products0_.Store_id=@p0;@p0 = 16 [Type: Int32 (0)] NHibernate: SELECT staff0_.Store_id as Store4_1_, staff0_.Id as Id1_, staff0_.Id as Id0_0_, staff0_.FirstName as FirstName0_0_, staff0_.LastName as LastName0_0_, staff0_.Store_id as Store4_0_0_ FROM [Employee] staff0_ WHERE staff0_.Store_id=@p0;@p0 = 16 [Type: Int32 (0)] NHibernate: INSERT INTO [Employee] (FirstName, LastName, Store_id) VALUES (@p0, @p1, @p2); select SCOPE_IDENTITY();@p0 = NULL [Type: String (4000)], @p1 = NULL [Type: String (4000)], @p2 = 16 [Type: Int32 (0)]

加载：stores = StoreRepository.GetAll（）

NHibernate: SELECT this_.Id as Id3_0_, this_.Name as Name3_0_ FROM [Store] this_ NHibernate: SELECT products0_.Store_id as Store2_1_, products0_.Product_id as Product1_1_, product1_.Id as Id1_0_, product1_.Name as Name1_0_, product1_.Price as Price1_0_ FROM StoreProduct products0_ left outer join [Product] product1_ on products0_.Product_id=product1_.Id WHERE products0_.Store_id=@p0;@p0 = 16 [Type: Int32 (0)] NHibernate: SELECT staff0_.Store_id as Store4_1_, staff0_.Id as Id1_, staff0_.Id as Id0_0_, staff0_.FirstName as FirstName0_0_, staff0_.LastName as LastName0_0_, staff0_.Store_id as Store4_0_0_ FROM [Employee] staff0_ WHERE staff0_.Store_id=@p0;@p0 = 16 [Type: Int32 (0)]

删除子项:(删除所选商店的员工）EmployeeRepository.Delete（员工）

NHibernate: SELECT employee0_.Id as Id0_1_, employee0_.FirstName as FirstName0_1_, employee0_.LastName as LastName0_1_, employee0_.Store_id as Store4_0_1_, store1_.Id as Id3_0_, store1_.Name as Name3_0_ FROM [Employee] employee0_ left outer join [Store] store1_ on employee0_.Store_id=store1_.Id WHERE employee0_.Id=@p0;@p0 = 35 [Type: Int32 (0)] NHibernate: SELECT products0_.Store_id as Store2_1_, products0_.Product_id as Product1_1_, product1_.Id as Id1_0_, product1_.Name as Name1_0_, product1_.Price as Price1_0_ FROM StoreProduct products0_ left outer join [Product] product1_ on products0_.Product_id=product1_.Id WHERE products0_.Store_id=@p0;@p0 = 16 [Type: Int32 (0)] NHibernate: SELECT staff0_.Store_id as Store4_1_, staff0_.Id as Id1_, staff0_.Id as Id0_0_, staff0_.FirstName as FirstName0_0_, staff0_.LastName as LastName0_0_, staff0_.Store_id as Store4_0_0_ FROM [Employee] staff0_ WHERE staff0_.Store_id=@p0;@p0 = 16 [Type: Int32 (0)] NHibernate: DELETE FROM [Employee] WHERE Id = @p0;@p0 = 35 [Type: Int32 (0)] NHibernate: DELETE FROM [Store] WHERE Id = @p0;@p0 = 16 [Type: Int32 (0)]

加载：stores = StoreRepository.GetAll（）

NHibernate: SELECT this_.Id as Id3_0_, this_.Name as Name3_0_ FROM [Store] this_

（没有结果，数据库为空）

EDIT1：

没有反向的SQL

程序启动

加载：存储stores = StoreRepository.GetAll（）

NHibernate: SELECT this_.Id as Id3_0_, this_.Name as Name3_0_ FROM [Store] this_

添加父级：将商店添加到空集合商店

保存：StoreRepository.SaveOrUpdate（存储）

NHibernate: SELECT store0_.Id as Id3_0_, store0_.Name as Name3_0_ FROM [Store] store0_ WHERE store0_.Id=@p0;@p0 = 0 [Type: Int32 (0)] NHibernate: INSERT INTO [Store] (Name) VALUES (@p0); select SCOPE_IDENTITY();@p0 = NULL [Type: String (4000)]

加载：stores = StoreRepository.GetAll（）

NHibernate: SELECT this_.Id as Id3_0_, this_.Name as Name3_0_ FROM [Store] this_ NHibernate: SELECT products0_.Store_id as Store2_1_, products0_.Product_id as Product1_1_, product1_.Id as Id1_0_, product1_.Name as Name1_0_, product1_.Price as Price1_0_ FROM StoreProduct products0_ left outer join [Product] product1_ on products0_.Product_id=product1_.Id WHERE products0_.Store_id=@p0;@p0 = 1 [Type: Int32 (0)] NHibernate: SELECT staff0_.Store_id as Store4_1_, staff0_.Id as Id1_, staff0_.Id as Id0_0_, staff0_.FirstName as FirstName0_0_, staff0_.LastName as LastName0_0_, staff0_.Store_id as Store4_0_0_ FROM [Employee] staff0_ WHERE staff0_.Store_id=@p0;@p0 = 1 [Type: Int32 (0)]

为所选商店添加子项：空子项集合

保存：StoreRepository.SaveOrUpdate（存储）

NHibernate: SELECT store0_.Id as Id3_0_, store0_.Name as Name3_0_ FROM [Store] store0_ WHERE store0_.Id=@p0;@p0 = 1 [Type: Int32 (0)] NHibernate: SELECT products0_.Store_id as Store2_1_, products0_.Product_id as Product1_1_, product1_.Id as Id1_0_, product1_.Name as Name1_0_, product1_.Price as Price1_0_ FROM StoreProduct products0_ left outer join [Product] product1_ on products0_.Product_id=product1_.Id WHERE products0_.Store_id=@p0;@p0 = 1 [Type: Int32 (0)] NHibernate: SELECT staff0_.Store_id as Store4_1_, staff0_.Id as Id1_, staff0_.Id as Id0_0_, staff0_.FirstName as FirstName0_0_, staff0_.LastName as LastName0_0_, staff0_.Store_id as Store4_0_0_ FROM [Employee] staff0_ WHERE staff0_.Store_id=@p0;@p0 = 1 [Type: Int32 (0)] NHibernate: INSERT INTO [Employee] (FirstName, LastName, Store_id) VALUES (@p0, @p1, @p2); select SCOPE_IDENTITY();@p0 = NULL [Type: String (4000)], @p1 = NULL [Type: String (4000)], @p2 = 1 [Type: Int32 (0)] NHibernate: UPDATE [Employee] SET Store_id = @p0 WHERE Id = @p1;@p0 = 1 [Type: Int32 (0)], @p1 = 1 [Type: Int32 (0)]

加载：stores = StoreRepository.GetAll（）

NHibernate: SELECT this_.Id as Id3_0_, this_.Name as Name3_0_ FROM [Store] this_ NHibernate: SELECT products0_.Store_id as Store2_1_, products0_.Product_id as Product1_1_, product1_.Id as Id1_0_, product1_.Name as Name1_0_, product1_.Price as Price1_0_ FROM StoreProduct products0_ left outer join [Product] product1_ on products0_.Product_id=product1_.Id WHERE products0_.Store_id=@p0;@p0 = 1 [Type: Int32 (0)] NHibernate: SELECT staff0_.Store_id as Store4_1_, staff0_.Id as Id1_, staff0_.Id as Id0_0_, staff0_.FirstName as FirstName0_0_, staff0_.LastName as LastName0_0_, staff0_.Store_id as Store4_0_0_ FROM [Employee] staff0_ WHERE staff0_.Store_id=@p0;@p0 = 1 [Type: Int32 (0)]

删除子项:(删除所选商店的员工）EmployeeRepository.Delete（员工）

NHibernate: SELECT employee0_.Id as Id0_1_, employee0_.FirstName as FirstName0_1_, employee0_.LastName as LastName0_1_, employee0_.Store_id as Store4_0_1_, store1_.Id as Id3_0_, store1_.Name as Name3_0_ FROM [Employee] employee0_ left outer join [Store] store1_ on employee0_.Store_id=store1_.Id WHERE employee0_.Id=@p0;@p0 = 1 [Type: Int32 (0)] NHibernate: SELECT products0_.Store_id as Store2_1_, products0_.Product_id as Product1_1_, product1_.Id as Id1_0_, product1_.Name as Name1_0_, product1_.Price as Price1_0_ FROM StoreProduct products0_ left outer join [Product] product1_ on products0_.Product_id=product1_.Id WHERE products0_.Store_id=@p0;@p0 = 1 [Type: Int32 (0)] NHibernate: SELECT staff0_.Store_id as Store4_1_, staff0_.Id as Id1_, staff0_.Id as Id0_0_, staff0_.FirstName as FirstName0_0_, staff0_.LastName as LastName0_0_, staff0_.Store_id as Store4_0_0_ FROM [Employee] staff0_ WHERE staff0_.Store_id=@p0;@p0 = 1 [Type: Int32 (0)] NHibernate: UPDATE [Employee] SET Store_id = null WHERE Store_id = @p0;@p0 = 1 [Type: Int32 (0)] NHibernate: DELETE FROM [Employee] WHERE Id = @p0;@p0 = 1 [Type: Int32 (0)] NHibernate: DELETE FROM [Store] WHERE Id = @p0;@p0 = 1 [Type: Int32 (0)]

加载：stores = StoreRepository.GetAll（）

NHibernate: SELECT this_.Id as Id3_0_, this_.Name as Name3_0_ FROM [Store] this_

（仍然;没有结果，数据库是空的）

计划窗口

所选商店的商店收藏和子集合被绑定到BindingSource / DataGridView / BindingNavigator，如下所示：

EDIT2

private static ISessionFactory CreateSessionFactory() { if (sessionFactory == null) { return Fluently.Configure() .Database(MsSqlConfiguration.MsSql2008 .ConnectionString(Properties.Settings.Default.FnhDbString) .Cache(c => c .UseQueryCache()).ShowSql()) .Mappings(m => m.FluentMappings.AddFromAssemblyOf<EmployeeMap>() .Conventions.Add(FluentNHibernate.Conventions.Helpers.DefaultLazy.Never()) .Conventions.Add(FluentNHibernate.Conventions.Helpers.DefaultCascade.All()) .ExportTo("D:/VB/")) .ExposeConfiguration(c => cfg = c) .BuildSessionFactory(); } return sessionFactory; }

EDIT3

我现在尝试了以下所有不同的映射（1-6）。如果没有级联约定，我会在所有替代方案上获得例外。我被迫手动删除参考？我认为不应该这样做。

// For all alternatives, configuration does not specify cascade-convention. // HasMany(x => x.Staff); // 1. add store, save, load, add employee, // save: TransientObjectException; Employee HasMany(x => x.Staff).Inverse(); // 2. As 1 // HasMany(x => x.Staff).Cascade.All(); // 3. Add store, Save, Load, Add Employee, Save, Load, // Delete Employee: ObjectDeletedException // HasMany(x => x.Staff).Inverse().Cascade.All(); // 4. As 3 // HasMany(x => x.Staff).Inverse().Cascade.AllDeleteOrphan(); // 5. As 3/4 // HasMany(x => x.Staff).Cascade.None(); // 6. As 1/2 // Exception of 1) // On StoreRepositorySaveOrUpdate(stores): TransientObjectException: // object references an unsaved transient instance - save the transient instance before flushing. // Type: FNHib_Test.Entities.Employee, Entity: FNHib_Test.Entities.Employee // Exception of 3) // On EmployeeRepository.Delete(employee); transaction.Commit() // ObjectDeletedException was unhandled: // deleted object would be re-saved by cascade // (remove deleted object from associations)[FNHib_Test.Entities.Employee#1]

EDIT5：

以上例外的结果：

1）存储是聚合根（无反向集）。由于没有级联：我需要在保存聚合时手动处理添加的子项。（好的）

2）Employee是聚合根（反向集）。仍然，因为没有级联：我需要手动处理添加的Employee，因为stores集合包含持久性和瞬态实体。所以1和2的线索就是cascade = none。逆是无关紧要的。（OK）

3）存储是聚合根（无反向集）。 Cascade = all，它在两个方向上都有效，不仅来自聚合根？因此，如果没有先删除它对父级的引用，我们就无法删除它。（也许OK）。

4）同样的原因3.反向对级联没有影响。（也许还可以）

5）与3相同的原因。

6）与1.相同。

如果这是结论。然后它意味着我们被迫在删除子项之前删除双向实体之间的引用。无论Inverse的设置如何。

所以：我看不出Inverse对双向关系有任何影响。？

EDIT6：

（呼吸......）甚至设置 emp.Store = null; 它仍然提供 ObjectDeletedException ：已删除的对象将通过级联重新保存（从关联中删除已删除的对象）[FNHib_Test.Entities.Employee＃1]

这是映射; HasMany（x =＆gt; x.Staff）.Cascade.All（）;

public static void Delete(Employee employee) { using (ISession session = FNH_Manager.OpenSession()) { using (ITransaction transaction = session.BeginTransaction()) { employee.Store = null; if (employee.Id != 0) { // var emp = session.Get(typeof(Employee), employee.Id); Employee emp = session.Get<Employee>( employee.Id); if (emp != null) { emp.Store = null; session.Delete(emp); transaction.Commit(); } } } } }

我想知道在保存瞬态实例时是否存在与实体-Id未设置相关的问题。这就是我在每次保存后加载的原因。但我不知道为什么他们没有定。正如我在此描述的那样：NHibernate: How is identity Id updated when saving a transient instance?

Answer 1

不要在映射中使用逆映射。 没有逆它应该没问题。

Answer 2

“我用常规Cascade.All配置”是什么意思？您使用的是Fluent NHibernate惯例吗？我在您的映射中看不到任何会导致Employee删除级联到附加商店的内容。我也没有看到为什么加载Employee会触发加载Store及其Staff and Products集合的任何原因。

对Delete方法的这种更改可能会解决问题，但它没有解决根本原因：

                  if (emp != null)
                  {
                    emp.Store = null;
                    session.Delete(emp);
                    transaction.Commit();
                  }

Answer 3

好的..最后..我发现至少有一个可行的解决方案。不确定这是否应该如何解决：

所需要的是从父列表中删除实例。孩子仍然可以参考父母，但不能以其他方式参考。所以，如下图所示：

<强> emp.Store.Staff.Remove（EMP）;

看起来有点尴尬。这只是一个正常的父子关系，我们试图删除孩子。但也许其他人可以用适当的知识来阐述......

顺便说一下，这是映射： HasMany（x =＆gt; x.Staff）.Cascade.All（）;

    public static void Delete(Employee employee)
    {
        using (ISession session = FNH_Manager.OpenSession())
        {
            using (ITransaction transaction = session.BeginTransaction())
            {

                if (employee.Id != 0) 
                { 
                  Employee emp = session.Get<Employee>(employee.Id);

                  if (emp != null)
                  {
                    emp.Store.Staff.Remove(emp);
                    session.Delete(emp);
                    transaction.Commit();
                  } 
                }
            }
        }
    }

NHibernate的;删除子项删除父项？

3 个答案: