从 Func 创建表达式 [英] Create Expression from Func

问题描述

我的代码中有一个 Func.我用它来选择某些属性.

I have a Func<TCollection, T> in my code. I use it to select certain properties.

在调用另一个方法时，我需要 Expression> 作为参数.

In a call to another method I need Expression<Func<TCollection, T>> as a parameter.

有什么方法可以将Func转换(或创建自)Expression?

Is there any way to convert (or create from) Func<TCollection, T> to Expression<Func<TCollection, T>> ?

谢谢

推荐答案

您不能基于方法重新创建表达式，因为表达式需要知道原始语句，而不是 IL.但是，您可以创建一个 Expresson，它对您的 func 进行方法调用，例如:

You can not recreate an expression based on a method since an expression needs to know the original statements, not IL. You can however create an Expresson which makes a method call to your func like:

Func<int> func = () => 1;
Expression<Func<int>> expression = Expression.Lambda<Func<int>>(Expression.Call(func.Method));

但是请注意，像 EF 这样的系统无法真正使用此功能

Note however that systems like EF can't really work with this

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