从LINQ到SQL的DataContext的SubmitChanges之前检索对象 [英] Retrieve object from LINQ-to-SQL DataContext before SubmitChanges

问题描述

我插入一个新的对象到LINQ到SQL的DataContext不调用的SubmitChanges（）尚未：

I insert a new object into LINQ-to-SQL DataContext without calling SubmitChanges() yet:

MyDataContext db = new MyDataContext();
MyObject newObject = new MyObject() 
{
   Id = 1,
   Name = "MyName"
};
db.MyObjects.InsertOnSubmit(newObject);

现在在我的code另一个地方，我想取出这个新的对象，即使它是不是在数据库中呢。所以，我通过同一DataContext的实例有，因为我相信，新的对象缓存里面。现在我想找回它。但是，这并不工作：​​

Now in another place in my code I want to retrieve this new object, even though it is not in the database yet. So I pass the same DataContext instance there, because I believe that the new object is cached inside it. And now I want to retrieve it. But this doesn't work:

MyObject newObject = db.MyObjects.Where(o => o.Id == 1).SingleOrDefault();

我怎么做我想要什么？这可能吗？

How can I do what I want? Is that possible?

推荐答案

尝试：

db.MyObjects.SingleOrDefault(o => o.Id == 1);

您会认为这将是相同的，但看到这两个连接问题：

You'd think this would be the same, but see these two connect issues:

• LINQ到SQL不使用缓存查找
• LINQ到SQL仍然为的往返ID查找（3.5SP1）

• LINQ-to-SQL doesn't use cache for lookup
• LINQ-to-SQL still roundtrips for ID lookups (3.5SP1)

如果不工作，我知道。单（O =＆GT; o.Id == 1） 3.5 SP1中工作（我不知道知道如果我试图 .SingleOrDefault（preD））。显然，。凡（O =＆GT; o.Id == 1）。单（）被固定在4.0 - 再次，我没有尝试过。凡（preD）.SingleOrDefault（）。

If that doesn't work, I know that the .Single(o => o.Id == 1) works in 3.5 SP1 (I don't know if I tried .SingleOrDefault(pred)). Apparently the .Where(o => o.Id == 1).Single() is fixed in 4.0 - again, I haven't tried .Where(pred).SingleOrDefault().

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