c# - 在 foreach 中删除对象

Question

我有一个异常(exception)说:

The object cannot be deleted because it was not found in the ObjectStateManager

当我在 ForEach 循环中调用 DeleteObject() 时。在谷歌搜索这个问题后，我还没有找到答案，而且我的代码也没有发现任何问题，如下所示。

DHEntity和DHEntityVersion之间存在一对多的关系。

public IList<DHEntity> GetAllDHEntity(Guid packId)
{
    using (DiaDataContext db = new DiaDataContext(ConnectionStrings.LogDB))
    {
        var subPackList = new List<DHEntity>();
        subPackList = db.DHEntities.Include(d=>d.DHEntityVersions).Where(p => p.PackageId == packId).ToList();
        return subPackList;
    }
}

private void Delete()
{
    using (DiaDataContext db = new DiaDataContext(ConnectionStrings.LogDB))
    {
        var subPacks = GetAllDHEntity(packId);////This method used another context. maybe it is the reason cause the problem .
        foreach (var subpack in subPacks)
        {
            var vList = db.DHEntityVersions.Where(v =>v.DHEntityId == subpack.ID).ToList();
            foreach (var version in vList)
            {
                db.DeleteObject(version);
            }
            db.DeleteObject(subpack);//the debugger stop here along with the exception I mentioned before.
        }
    }
}

Answer 1

问题是对象来自另一个数据上下文。

用于获取项目的上下文 GetAllDHEntity 不是用于Delete 的上下文，这就是该对象的状态不存在的原因。