typescript - rootReducer = combineReducer 使用 typescript 生成类型 'Never'

Question

组合我的 reducer 时，类型将根 reducer 设置为 Reducer1: never, Reducer2: never
例子:

const rootReducer = combineReducers({
  stories: storyReducer,
  archivedStories: archiveReducer,
});

export type RootState = ReturnType<typeof rootReducer>;

storyReducer (IStory[], StoryActionTypes)
archiveReducer (number[], ArchiveActionTypes)
类型反而出现了，
故事:从不；
存档故事:从不
我遵循了另一个堆栈溢出建议并尝试指定类型。

const rootReducer: Reducer<CombinedState<{stories: IStory[]; archivedStories: number[];}>, StoryActionTypes | ArchiveActionTypes> = combineReducers({
  stories: storyReducer,
  archivedStories: archiveReducer,
});

但它仍然试图将它们映射到 Never
输入 'Reducer , FetchStoriesAction | AddStoriesAction | ArchiveStoryAction>' 不可分配到类型 'Reducer<{ stories: IStory[];存档故事:数字[]； }, FetchStoriesAction | AddStoriesAction | ArchiveStoryAction>'。
参数“state”和“prevState”的类型不兼容。
输入'{故事:IStory[];存档故事:数字[]； }' 不可分配给类型 'CombinedState<{ stories: never;存档故事:从不； }>'。
输入'{故事:IStory[];存档故事:数字[]； }' 不能分配给类型 '{ stories: never;存档故事:从不； }'。
属性(property)“故事”的类型是不兼容的。
类型 'IStory[]' 不可分配给类型 'never'.ts(2322)
这里有什么问题？或者如何正确指定类型？我的目标是在 IStory[] 负载上使用 .filter。
这些是 reducer :
故事 reducer

const INITIAL_STATE: IStory[] = []
  
const applyAddStories = (state: IStory[], action: StoryActionTypes) => action.payload;

export const storyReducer = (
  state = INITIAL_STATE,
  action: StoryActionTypes
) => {
  switch (action.type) {
    case STORIES_ADD : {
      return applyAddStories(state, action)
    }
    default:
      return state;
  }
};

归档 reducer

const INITIAL_STATE: number[] = []

const applyArchiveStory = (state: number[], action: ArchiveActionTypes) => [
  ...state,
  action.payload,
];

export const archiveReducer = (
  state = INITIAL_STATE,
  action: ArchiveActionTypes

) => {
  switch (action.type) {
    case STORY_ARCHIVE: {
      return applyArchiveStory(state, action);
    }
    default:
      return state;
  }
};

export default archiveReducer;

Answer 1

我建议强制执行 reducer 的返回类型。这是我喜欢做的事情，因为它有助于对 reducer 实现进行类型检查:

//                                                           here
//                                                              v
function storyReducer(state: IStory[], action: StoryActionTypes): IStory[] {
  // ...
}

您不需要显式键入reducer，它只适用于您的原始代码:

const rootReducer = combineReducers({
  stories: storyReducer,
  archivedStories: archiveReducer,
});

export type RootState = ReturnType<typeof rootReducer>;

这是一个演示结果的操场: link