nhibernate :具有相同标识符值的不同对象已经与会话关联:2，实体: [英] nhibernate : a different object with the same identifier value was already associated with the session: 2, of entity:

问题描述

当我尝试将我的公司"实体保存在我的 mvc 应用程序中时出现以下错误

I am getting the following error when i tried and save my "Company" entity in my mvc application

具有相同标识符值的不同对象已与会话关联:2，实体:

我正在使用 IOC 容器

I am using an IOC container

private class EStoreDependencies : NinjectModule
    {
        public override void Load()
        {

            Bind<ICompanyRepository>().To<CompanyRepository>().WithConstructorArgument("session",
                                                                                       NHibernateHelper.OpenSession());
        }
    }

我的公司存储库

public class CompanyRepository : ICompanyRepository
{
    private ISession _session;

    public CompanyRepository(ISession session)
    {
        _session = session;
    }    

    public void Update(Company company)
    {

        using (ITransaction transaction = _session.BeginTransaction())
        {

            _session.Update(company);
            transaction.Commit();
        }
    }

}

和会话助手

public class NHibernateHelper
{
    private static ISessionFactory _sessionFactory; 
    const string SessionKey = "MySession";


    private static ISessionFactory SessionFactory
    {
        get
        {
            if (_sessionFactory == null)
            {
                var configuration = new Configuration();
                configuration.Configure();
                configuration.AddAssembly(typeof(UserProfile).Assembly);
                configuration.SetProperty(NHibernate.Cfg.Environment.ConnectionStringName,
                                          System.Environment.MachineName);
                _sessionFactory = configuration.BuildSessionFactory();
            }
            return _sessionFactory;
        }
    }

    public static ISession OpenSession()
    {
        var context = HttpContext.Current;
        //.GetCurrentSession()

        if (context != null && context.Items.Contains(SessionKey))
        {
            //Return already open ISession
            return (ISession)context.Items[SessionKey];
        }
        else
        {
            //Create new ISession and store in HttpContext
            var newSession = SessionFactory.OpenSession();
            if (context != null)
                context.Items[SessionKey] = newSession;

            return newSession;
        }
    }
}

我的 MVC 操作

    [HttpPost]
    public ActionResult Edit(EStore.Domain.Model.Company company)
    {

            if (company.Id > 0)
            {

                _companyRepository.Update(company);
                _statusResponses.Add(StatusResponseHelper.Create(Constants
                    .RecordUpdated(), StatusResponseLookup.Success));
            }
            else
            {
                company.CreatedByUserId = currentUserId;
               _companyRepository.Add(company);
            }


        var viewModel = EditViewModel(company.Id, _statusResponses);
        return View("Edit", viewModel);
    }

推荐答案

我知道这有点晚了，您可能已经找到了解决方案，但也许其他人可以从中受益...

I know this is a bit late and you might already found the solution, but maybe others could benefit from it...

当您更新保存在缓存中的实体实例时，nHibernate 会引发此错误.基本上 nHibernate 将您的对象在加载后存储在缓存中，因此下一次调用将从缓存中获取它.如果更新缓存中存在的实例，nHibernate 会抛出此错误，否则可能会导致脏读和加载对象旧副本时发生冲突.要解决此问题，您需要使用 Evict 方法从缓存中删除对象，例如:

This error is raised from nHibernate when you are updating an instance of an Entity that is saved on the Cache. Basically nHibernate stores your objects on the cache once you loaded it, so next calls would get it from the cache. If you update an instance that is present on the cache nHibernate throws this error otherwise it could cause dirty reads and conflicts regarding loading the old copy of the object. To get around this, you need to remove the object from the cache using the Evict method like:

public ActionResult Edit(EStore.Domain.Model.Company company) 
{ 

        if (company.Id > 0) 
        { 
            **ISession.Evict(company);**
            _companyRepository.Update(company);

希望这会有所帮助.

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