typescript - 强制对象包含枚举的所有键，并且仍然对其值进行类型推断

Question

我有一个对象，我想强制它包含一个枚举的所有键，我还想推断它的值的类型。 所以如果我这样做:

enum RequiredKeys {
    A = 'a',
    B = 'b'
}
const objectThatShouldContainAllRequiredKeys = {
    [RequiredKeys.A]: (id: string) => {}
};
// Argument of type '123' is not assignable to parameter of type 'string'
// Which is great, that's exactly what I want. 
objectThatShouldContainAllRequiredKeys[RequiredKeys.A](123);

但是现在，我尝试强制执行对象键，我尝试的每个解决方案都会破坏类型推断。例如:

enum RequiredKeys {
    A = 'a',
    B = 'b'
}
// Property 'b' is missing in type '{ a: (id: string) => void; }' but required in type 'Record<RequiredKeys, Function>'.
// Which is great, that's exactly what I want
const objectThatShouldContainAllRequiredKeys: Record<RequiredKeys, Function> = {
    [RequiredKeys.A]: (id: string) => {}
};
// No error here, which is less great...
objectThatShouldContainAllRequiredKeys[RequiredKeys.A](123);

知道如何享受两个世界吗？对象是否强制执行枚举中的所有键并推断对象值？ 谢谢!!

Answer 1

您可以创建带有类型参数的标识函数，将类型参数限制为具有所需的键，因此 typescript 将验证传递的对象键并推断其值的类型:

const createWithRequiredKeys = <T extends Record<RequiredKeys, unknown>>(obj: T) => obj;

const withRequiredKeys = createWithRequiredKeys({
    [RequiredKeys.A]: (id: string) => {},
    [RequiredKeys.B]: 'foo',
}); 

// withRequiredKeys is { a: (id: string) => void; b: string; }

withRequiredKeys[RequiredKeys.A](123); // 'number' is not assignable to parameter of type 'string'

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