为什么是当我删除子级(员工)时,父级(商店)也被删除?
我配置为约定 Cascade.All.
The 用户输入序列很简单:
- 从空数据库开始
- 添加家长
- 保存,加载(加载=重新加载完整对象图)
- 添加一个孩子
- 保存、加载
- 删除子项
- 结果:数据库为空。 (父级已删除)
这可能是一个基本的映射错误,因为这是我第一次使用 NHibernate。我想存储为聚合根,并认为通过not在 Store.Staff 属性上设置 Inverse,则 Store 表将负责保存,从而负责保存聚合根。这是一个误解吗?实际上,无论我是否使用 Inverse,我仍然会得到相同的结果。所以也许
这不是问题,但我也想了解这一点。
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();
}
}
}
}
}
Mappings
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; }
}
程序伪代码和生成的“SQL”:
程序启动
加载:商店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(stores)
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)]
添加子项:到空子集合,针对选定的商店
保存:StoreRepository.SaveOrUpdate(stores)
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(employee)
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:
没有逆向的 SQL
程序启动
加载:商店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(stores)
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)]
添加子项:到空子集合,针对选定的商店
保存:StoreRepository.SaveOrUpdate(stores)
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(employee)
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,数据库为空)
程序窗口
所选商店的商店集合和子集合绑定到 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
我现在已经尝试了下面的所有不同映射(1-6)。如果没有级联约定,我对所有替代方案都会遇到例外。我是吗被迫手动删除引用?我认为不应该被要求。
// 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:
对上述异常情况的调查结果:
1) 存储为聚合根(无逆集)。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(逆集)。尽管如此,由于没有级联:我需要手动处理添加的 Employee,只是因为商店集合包含持久实体和瞬态实体。所以1和2的线索就是cascade = none。反之则无关紧要。 (好的)
3)存储为聚合根(无逆集)。 Cascade=all,而且它是双向工作的,不仅仅是从聚合根开始?因此,如果不首先删除子级对父级的引用,我们就无法删除子级。 (也许OK)。
4)与3相同的原因。逆对级联没有影响。 (也许OK)
5) 原因与3相同。
6) 与 1 相同。
如果这是结论的话。那么这意味着我们被迫在删除子实体之前删除双向实体之间的引用。无论 Inverse 的设置如何。
So: 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;它仍然给对象删除异常:
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]
这是与地图相关的;HasMany(x => 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未设置实体 ID 相关的问题。这就是为什么我在每次保存后加载。但我不知道为什么它们没有被设置。正如我在这里所描述的:NHibernate:保存临时实例时如何更新身份ID? https://stackoverflow.com/questions/4896001/nhibernate-how-is-identity-id-updated-when-saving-a-transient-instance