Question

除了“ errors”属性外，我需要返回带有任何键的对象。

我需要使用runtypes来定义类似{[string]: any, errors: never} | {errors: {message: string}[]}的网络响应。但首先，我想通过类型系统对其进行定义。

type RespSuccess = {
  [key: string]: any;
  errors: never;
};
type RespError = {
  errors: { message: string }[];
};

async function callNetwork<I extends any[], O extends RespSuccess | RespError>(
  fn: (...a: I) => O,
  ...a: I
): Promise<RespSuccess> {
  const resp = await fn(...a);

  if ("errors" in resp)
    throw new Error(resp.errors.map(({ message }) => message).join());

  return resp; // Error: Type 'O' is not assignable to type 'RespSuccess'.
}

最奇怪的是在这里：

// after typeguard the resp is still may be RespSuccess
...throw new Error(resp // const resp: O extends RespSuccess | RespError

// but the errors infer well
...throw new Error(resp.errors // (property) errors: {message: string;}[]

除了TypeScript，我会检查我是否完全返回RespSuccess

Typescript对“从不”属性的奇怪推断

0 个答案: