NHibernate将保存,但不会加载实体

Question

我在NHibernate 2.1.2.4000 GA和最新版本的FluentNHibernate上收到了一个非常奇怪的错误.我可以保存一个实体,但在调用Flush()和Clear()后无法加载它.

这是我的实体:

public class Application
{
 public int Id { get; set; }
 public string Name { get; set; }
 public string KeyName { get; set; }
 public string Description { get; set; }
 public string Url { get; set; }

 public override bool Equals(object obj)
 {
  if (null != obj && obj is Application)
  {
   return ((Application)obj).Id == this.Id;
  }
  else
  {
   return base.Equals(obj);
  }
 }
}

我的配置图:

public class ApplicationMap : ClassMap
{
 public ApplicationMap()
 {
  Table("[Application]");

  Not.LazyLoad();

  Id(x => x.Id, "ApplicationId")
   .GeneratedBy.Identity();
  Map(x => x.Name, "ApplicationName")
   .Nullable()
   .Length(50);
  Map(x => x.Description, "ApplicationDescription")
   .Nullable()
   .Length(200);
  Map(x => x.KeyName, "ApplicationKeyName")
   .Nullable()
   .Length(50);
  Map(x => x.Url, "ApplicationLink")
   .Nullable()
   .Length(50);
 }
}

我如何创建我的ISession:

var _sessionFactory = Fluently.Configure()
 .Database(
  SQLiteConfiguration.Standard.InMemory()
  .ProxyFactoryFactory(typeof(ProxyFactoryFactory)))
 .Mappings(
  m => m.FluentMappings.AddFromAssemblyOf())
 .ExposeConfiguration(cfg => Config = cfg)
 .BuildSessionFactory(); 

var _session = _sessionFactory.OpenSession();

这是不可行的代码:

Application myApp = new Application()
{
 Id = 1,
 Description = "MyApp",
 KeyName = "MyApp",
 Name = "My App",
 Url = "http://www.myapp.com"
};

_session.Save(myApp);
var idMyApp = myApp.Id;
_session.Flush();
_session.Clear();
_session = NHibernateHelper.CreateSession();
var a = _session.Load(idMyApp);

我尝试从数据库加载对象时得到的异常是:

Test method HNI.Portal.Test.MappingTests.RoleMap.CanCorrectMapRole threw exception:  NHibernate.ObjectNotFoundException: No row with the given identifier exists[HNI.Portal.Core.Entities.Application#1].

和StackTrace:

NHibernate.Impl.SessionFactoryImpl.DefaultEntityNotFoundDelegate.HandleEntityNotFound(String entityName, Object id)
NHibernate.Event.Default.DefaultLoadEventListener.Load(LoadEvent event, IEntityPersister persister, EntityKey keyToLoad, LoadType options)
NHibernate.Event.Default.DefaultLoadEventListener.ProxyOrLoad(LoadEvent event, IEntityPersister persister, EntityKey keyToLoad, LoadType options)
NHibernate.Event.Default.DefaultLoadEventListener.OnLoad(LoadEvent event, LoadType loadType)
NHibernate.Impl.SessionImpl.FireLoad(LoadEvent event, LoadType loadType)
NHibernate.Impl.SessionImpl.Load(String entityName, Object id)
NHibernate.Impl.SessionImpl.Load(Type entityClass, Object id)
NHibernate.Impl.SessionImpl.Load[T](Object id)

我不确定是否应该调用Flush()和Clear()(仍然在研究它),但是在使用PersistenceSpecification编写测试时我遇到了这个错误.这就是PersistenceSpecification在CheckList()断言上的作用,以验证列表是否正确保存,这不适合我.我进入了代码,并得到了这个repro.

应用程序行已正确插入数据库,但不会再次加载.它发生在SqlServer和Sqlite上.

希望你们能帮助我.

非常感谢!

Answer 1

您正在设置 id，但它是一个身份。您不应该设置它，SQL 会为您完成此操作。

使用相同的会话而不是创建新会话，并使用 Get 而不是 Load 进行检索。

关于Load和Get之间的区别： http://ayende.com/Blog/archive/2009/04/30/nhibernate-ndash-the-difference- Between-get-load-and-querying-by.aspx