EF 4插入实体与现有实体的关系

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个场景，将我现有的操作链接到从操作继承的内部操作..但在任何一种情况下，他都会给我一个错误，就像他想在数据库中插入一个新操作一样（dbo.Operations可以接受“Action”NULL值）但实体已经存在..有人可以请给我一个黄金法则..插入有关系的实体..在EF中是否存在。这让我发疯了！

Cordialy， 于连。

Answer 1

如果我理解正确（您尝试更新关系），则可以使用存根技术：

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();