在打字稿中编写类型安全的“选择"函数 [英] Write a typesafe 'pick' function in typescript

问题描述

lodash具有选择功能，用法如下:

lodash has the pick function which is used as follows:

var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pick(object, ['a', 'c']);
// => { 'a': 1, 'c': 3 }

我想在打字稿中写一个对此类型安全的版本.

I would like to write a type-safe version of this in typescript.

此功能的使用应为

pick(object, o => o.a, o.b)

我们的目标是不要两次指定相同的键，同时又要保护类型的安全性.

The goal is not to specify the same keys twice, and at the same time conserve type safety.

这有可能实现吗?

推荐答案

听起来像您正在寻找

Sounds like you might be looking for the Pick type. Would something like this work for you?

function pick<T, K extends keyof T>(obj: T, ...keys: K[]): Pick<T, K> {
  const ret: any = {};
  keys.forEach(key => {
    ret[key] = obj[key];
  })
  return ret;
}

const o = {a: 1, b: '2', c: 3}
const picked = pick(o, 'b', 'c');

picked.a; // not allowed
picked.b  // string
picked.c  // number

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