C# 一个实体对象不能被多个IEntityChangeTracker实例引用，即使我分离了它

我用的是EF。我将实体保存到缓存中

我在放入缓存之前分离每个实体

并在从缓存获取后将其附加到新的objectContext

我在高点使用

语句（在我的BL类中，根据每个请求）

但我得到了这个错误：

System.InvalidOperationException: An entity object cannot be referenced by multiple instances of IEntityChangeTracker.
at System.Data.Objects.ObjectContext.VerifyContextForAddOrAttach(IEntityWrapper wrappedEntity)
at System.Data.Objects.ObjectContext.AttachSingleObject(IEntityWrapper wrappedEntity, EntitySet entitySet, String argumentName)
at System.Data.Objects.ObjectContext.AttachTo(String entitySetName, Object entity)
at System.Data.Entity.Internal.Linq.InternalSet`1.ActOnSet(Action action, EntityState newState, Object entity, String methodName)
at System.Data.Entity.Internal.Linq.InternalSet`1.Attach(Object entity)
at System.Data.Entity.DbSet`1.Attach(TEntity entity)
at Conduit.Mam.ClientService.DAL.MamData.MamDataRepository.GetMamData(String stamp, MaMDBEntities maMDBEntities) in d:\Builds\TFS\9\221\Sources\Server\ClientServices\Dev\ClientService 1.3\ServiceDAL\MamData\MamDataRepository.cs:line 56
at Conduit.Mam.ClientService.BLL.MamDataManager.GetMamData() in d:\Builds\TFS\9\221\Sources\Server\ClientServices\Dev\ClientService 1.3\Conduit.Mam.ClientService.BLL\MamDataManager.cs:line 57
at Conduit.Mam.ClientService.BLL.AppsDataManager.GetClientRelevantsApps(List`1 appsData) in d:\Builds\TFS\9\221\Sources\Server\ClientServices\Dev\ClientService 1.3\Conduit.Mam.ClientService.BLL\AppsDataManager.cs:line 107
at Conduit.Mam.ClientService.Service.Controllers.ClientDataController.GetAppsData() in d:\Builds\TFS\9\221\Sources\Server\ClientServices\Dev\ClientService 1.3\Conduit.Mam.ClientService.Service\Controllers\ClientDataController.cs:line 58   

这是我的分离+附加代码：
使用

将objectContext注入此处：

public static Group GetMamData(string stamp, MaMDBEntities maMDBEntities)
    {
        Group group = MamDataCacheManager.GetMamData(stamp);

        if (group == null)
        {
            //was not found in the cache
            //check for aveilable test with status 'start' - 1
            group = GetGroupsFromDb(stamp, maMDBEntities);

            if (group != null)
            {
                maMDBEntities.Entry(group).State = EntityState.Detached;

                MamDataCacheManager.InsertMamData(stamp, group);

            }
        }

        //option B: attache a new context
        if (maMDBEntities.Entry(group).State == EntityState.Detached)
        {
            maMDBEntities.Groups.Attach(group);
        }

        return group;
    }

第一次（将新实体从数据库获取到缓存中）：

该实体被分离并附加到同一contextObjec

第二次（从缓存中获取实体）

它只附加到一个新的contextObject

---

我需要做任何额外的步骤吗？我的分离是否缺少任何内容？

分离只影响传递给方法的特定对象。如果要分离的对象在对象上下文中具有相关对象，则不会分离这些对象