Question

是否可以通过这样的方式键入字符串数组，使得该数组只能是给定对象中的有效属性路径？类型定义应该适用于所有深度嵌套的对象。

示例：

const object1 = {
    someProperty: true
};
const object2 = {
    nestedObject: object1,
    anotherProperty: 2
};

type PropertyPath<Type extends object> = [keyof Type, ...Array<string>]; // <-- this needs to be improved

// ----------------------------------------------------------------

let propertyPath1: PropertyPath<typeof object1>;

propertyPath1 = ["someProperty"]; // works
propertyPath1 = ["doesntExist"]; // should not work

let propertyPath2: PropertyPath<typeof object2>;

propertyPath2 = ["nestedObject", "someProperty"]; // works
propertyPath2 = ["nestedObject", "doesntExist"]; // should not work
propertyPath2 = ["doesntExist"]; // should not work

Link to TypeScript playground

Answer 1

在the answer to the question this duplicates中，您可以使用递归Paths<>或Leaves<>类型的别名，这取决于您是否要支持所有从根开始并在树中任何地方结束的路径（Paths<>），或者如果您只想支持从树的根部开始（Leaves<>）结束的路径：

type AllPathsObject2 = Paths<typeof object2>;
// type AllPathsObject2 = ["nestedObject"] | ["nestedObject", "someProperty"] | 
//  ["anotherProperty"]

type LeavesObject2 = Leaves<typeof object2>;
// type LeavesObject2 = ["nestedObject", "someProperty"] | ["anotherProperty"]

我假设它是Paths，但是如果适合您的情况，您可以将其更改为Leaves。这是您得到的行为，与您的要求相符：

let propertyPath1: Paths<typeof object1>;
propertyPath1 = ["someProperty"]; // works
propertyPath1 = ["doesntExist"]; // error!
//               ~~~~~~~~~~~~~~

let propertyPath2: Paths<typeof object2>;
propertyPath2 = ["nestedObject", "someProperty"]; // works
propertyPath2 = ["nestedObject", "doesntExist"]; // error!
//                               ~~~~~~~~~~~~~
propertyPath2 = ["doesntExist"]; // error!
//               ~~~~~~~~~~~~~

好的，希望能有所帮助；祝你好运！

Link to code

Answer 2

可以使用箭头功能

const object1 = {
    someProperty: true
};
const object2 = {
    nestedObject: object1,
    anotherProperty: 2
};

type PropertyPath<Type extends object> = (x: Type) => any;

let propertyPath1: PropertyPath<typeof object1>;

propertyPath1 = (x) => x.someProperty; // works
propertyPath1 = (x) => x.doesntExist; // should not work

let propertyPath2: PropertyPath<typeof object2>;

propertyPath2 = (x) => x.nestedObject.someProperty; // works
propertyPath2 = (x) => x.nestedObject.doesntExist; // should not work
propertyPath2 = (x) => x.doesntExist; // should not work

Playground Link

对象属性路径的TypeScript类型定义

2 个答案: