实体对象不能由IEntityChangeTracker的多个实例被引用 [英] An entity object cannot be referenced by multiple instances of IEntityChangeTracker

问题描述

我用EF作为ORM。

我处置的ObjectContext 在每次请求。

我保存实体缓存层，因为我的服务获取大量的流量。

I save the entities in a cache layer, as my service gets lots of traffic.

我有时会得到错误的ObjectContext已经部署对于一些实体，我从缓存中得到。

I got sometimes get the error objectContext already disposed for some entities that I got from the cache.

我加入这个code从缓存中retrived的元素

I have added this code to elements that were retrived from the cache

if (maMDBEntities.Entry(group).State == EntityState.Detached)
{
    maMDBEntities.Groups.Attach(group);
}

但现在我有时会收到此错误：

but now I sometimes get this error:

这是实体对象不能由IEntityChangeTracker的多个实例被引用。

An entity object cannot be referenced by multiple instances of IEntityChangeTracker.

使用附加（）从首位不正确的解决方案？

Was using Attach() an incorrect solution from the first place?

推荐答案

当我们告诉你在你的其他问题（<一个href=\"http://stackoverflow.com/questions/14724397/will-efattachentity-will-solve-objectcontext-is-already-desposed\">will EF ::附加（实体）将解决的ObjectContext已经desposed？），你必须将其连接到另一个上下文之前分离的实体！

As we told you in your other question (will EF::attach(entity) will solve objectContext is already desposed?), you have to detach the Entities before attaching it to another Context!

如果 maMDBEntities 从这个语境点视图一个新的上下文（不是之一，它装载的数据），该EntityState没有附加。所以你的检查是不够的。

If maMDBEntities is a new Context (not the one, which loaded the data), the EntityState is not "attached" from this Contexts point-of-view. So your check is not sufficient.

本 maMDBEntities.Entry（集团）.STATE == EntityState.Detached 将总是是一个方面，它没有加载正确实体。

This maMDBEntities.Entry(group).State == EntityState.Detached will always be true for an Context, which did not load the Entity.

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