NHibernate HQL元组结果 [英] NHibernate hql tuple result

问题描述

hql = "select f, b from Foo f, Bar b"

var resultList = session.CreateQuery(hql).List<object[]>();

结果列表项是一个数组，其中[0]是Foo类型，[1] id是类型栏

result list item is an array where [0] is of type Foo and [1] id of Type Bar

有没有一种方法可以使用Tuple< Foo，Bar> (或其他通用类)作为由object []插入的通用参数，因此可以跳过强制转换吗?

Is there a way to use Tuple<Foo,Bar> (or other generic class ) as generic parameter insted of object[] so one can skip casting?

推荐答案

可以，例如:

// The new Tuple<Foo, Bar>(foo, bar) constructor
Type constructor = typeof(Tuple<Foo, Bar>).GetConstructors()[0];

然后

.SetResultTransformer(Transformers.AliasToBeanConstructor(constructor));

在.List()

附录

我查看了我的代码(因为一两年前已经完成了:))，我注意到我更喜欢

I've looked at my code (because I've already done this one or two years ago :) ), and I noticed that I preferred

Type constructor = typeof(Tuple<Foo, Bar>).GetConstructor(new[] { typeof(Foo), typeof(Bar) });

对此有一个很好的理由:现在(从.NET 4.5.1开始)，有一个Tuple<T1, T2>的公共构造函数，即new Tuple(T1 t1, T2 t2). 没有隐式或显式保证，在.NET的将来版本中，不会有Tuple<T1, T2>的无参数公共构造函数来返回空"元组.较长的GetConstructor格式可确保始终采用正确的"构造函数.

There is a perfectly good reasoning for this: now (as of .NET 4.5.1) there is a single public constructor for Tuple<T1, T2>, that is new Tuple(T1 t1, T2 t2). There is no implicit or explicit guarantee that in a future version of .NET there won't be a parameterless public constructor of Tuple<T1, T2> that will return an "empty" tuple. The longer GetConstructor form guarantees that the "right" constructor will always be taken.

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