EF 4 插入与现有实体相关的实体

Question

using (EntitiesContainer db = new EntitiesContainer())
{
    Language language = db.Languages.SingleOrDefault(x => x.Culture == _session.Language);
    Language language2 = new Language { Id = action.Language.Id };
    Operation operation = new Operation { Id = action.Operation.Id };
    //Operation operation = db.Operations.SingleOrDefault(x => x.Id == action.Operation.Id);

    if (!language.Id.Equals(language2.Id))
    {
        db.Languages.Attach(language2);
        action.Language = language2;
    }
    else
    {
        action.Language = language;
    }

    db.Operations.Attach(operation);

    //db.ObjectStateManager.ChangeObjectState(operation, System.Data.EntityState.Unchanged);

    action.Operation = operation;
    //operation.Internals.Add(action);

    action.CurrentDetail.Language = language;
    action.CurrentDetail.Id = Guid.NewGuid();

    action.Id = Guid.NewGuid();

    db.SaveChanges();
}

你好，我在评论中尝试所有这种情况，将我现有的操作链接到从操作继承的内部操作..但在任何这种情况下，他都会向我抛出一个错误，就像他想在数据库中插入一个新操作（dbo.Operations 可以接受“Action”NULL 值），但实体已经存在。有人可以给我黄金吗？规则 .. 插入具有关系 .. 存在或不存在于 EF 中的实体。这让我发疯！

诚挚地， 朱利安.

Answer 1

如果我理解正确（你试图更新关系），你可以使用存根技术：

Language lang = new Language { Id = action.language_id }; // create stub with ID
db.Languages.Attach(lang); // attach stub to graph
action.language = lang; // update relationship
db.SaveChanges();