在Linq-to-Nhibernate中，是否可以在.Select()之后使用.Fetch()? [英] In Linq-to-Nhibernate, is it possible to use .Fetch() after a .Select()?

问题描述

如果我的对象A包含对对象B的多对一引用，而对象B包含对象C的一对多集合，请考虑以下查询:

If I had an Object A that contained a many-to-one reference to Object B, where Object B contained a one-to-many collection of Object C... consider the following query:

IQueryable<A> query = getIQueryableSomehow();

List<B> resultList = query.Where(A => A.whatever == something).Select(A => A.B).Fetch(B => B.C).ToList();

我想做与此类似的事情，但是我不断使用此代码获取空引用异常.是否有偷偷摸摸的技巧来实现这种查询并获取一堆Object B集合，还是不可能?

I want to do something similar to this, but I keep getting a null reference exception with this code. Is there a sneaky trick to achieve this kind of query AND fetch a bunch of Object B collections, or is it impossible?

谢谢！

推荐答案

您可以指定Fetch before来加载所有A，B，C，然后选择Bs

you can specify Fetch before to load all A,B,C and then select the Bs

List<B> resultList = query
    .Where(A => A.whatever == something)
    .Fetch(A => A.B).ThenFetch(B => B.C)
    .Select(A => A.B)
    .ToList();

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