Typescript 如何在将值限制为已知集的同时推断映射的类型？

我正在尝试创建从一组字符串键到一组特定字符串的映射：

type Datum = { LOCATION: string, GENDER: number }

export const fieldKeys: Record<strings, keyof Datum> = {
  country: "LOCATION",
  gender: "GENDER"
};

但是，由于

字段键

记录键是任意字符串，而不是一组众所周知的属性，因此允许误用：

// Passes type checker but is a bug.
const bug = d[fieldKeys.doesNotExist]

此外，当通过字段键访问时，属性的推断类型是所有可能的数据属性值的并集类型：

// Inferred type is 'string | number' instead of string.
const shouldBeString = d[fieldKeys.country] 

理想情况下，TypeScript应该推断记录的键，但这样的代码是不允许的，因为它是递归的：

export const fieldKeys: Record<keyof (typeof fieldKeys), keyof Datum> = {
  country: "LOCATION",
  gender: "GENDER"
};

---

有人知道怎么做吗？

你能解释一下你想做什么吗？键

国家

和字符串

位置

如何连接？为什么它不允许任意字符串？@ritaj我试图扩展描述。现在更清楚了吗？所有这些片段似乎都有效，所以我不确定我是否理解这个问题：我更新了描述，希望能让问题更清楚。

export const fieldKeys: Record<keyof (typeof fieldKeys), keyof Datum> = {
  country: "LOCATION",
  gender: "GENDER"
};

const keyOf = <D, K extends keyof D>(k: K): K => k

export const fieldKeys = {
  country: keyOf<Datum, "LOCATION">("LOCATION"),
  gender: keyOf<Datum, "GENDER">("GENDER")
} as const;

type Datum = { LOCATION: string, GENDER: number }

export const fieldKeys = {
  country: "LOCATION",
  gender: "GENDER",

  // Requirement: Type checker complains that NODATUMPROPERTY is is not a property of Datum.
  noDatumProperty: "NODATUMPROPERTY"
};

const d: Datum = { LOCATION: "Germany", GENDER: 1 }

// Requirement: inferred type is 'string'
const country = d[fieldKeys.country]

// Requirement: Type checker complains about non-existing property in fieldKeys.
const bug1 = d[fieldKeys.doesNotExist]