带有打字稿的递归类型

Question

我想创建一个类型，它是一个包含字符串的对象或包含字符串或对象的对象，...

所以我所做的就是创建一个这样的类型：

type TranslationObject = { [key: string]: string | TranslationObject };

但是在reduce中使用它时，这就是导致错误的地方

Object.keys(newTranslations).reduce((acc: TranslationObject, translationKey: string): TranslationObject => {
    return {
      ...acc,
      [translationKey]: {
        ...acc[translationKey] as TranslationObject,
        [namespace]: {
          ...(acc[translationKey][namespace] as TranslationObject), // Error at this line
          ...newTranslations
        }
      }
    }
  }, translations);

错误是

TS7053: Element implicitly has an 'any' type because expression of type 'string' can't be used to index type 'string | TranslationObject'.   No index signature with a parameter of type 'string' was found on type 'string | TranslationObject'.

所以我的类型要么是字符串类型，要么是对象类型，但在这种情况下，我希望它是对象部分，但我无法真正弄清楚。

Answer 1

您需要在 acc[translationKey] 之后添加为 TranslationObject，因为您无法尝试从字符串中获取密钥。

Object.keys(newTranslations).reduce((acc: TranslationObject, translationKey: string): TranslationObject => {
    return {
      ...acc,
      [translationKey]: {
        ...acc[translationKey] as TranslationObject,
        [namespace]: {
          ...((acc[translationKey] as TranslationObject)[namespace] as TranslationObject), 
          ...newTranslations
        }
      }
    }
  }, translations);