Question

我一直在学习 redux，但我的状态在选择器调用期间返回 undefined 时遇到了问题。

一些代码：

选择器： export const selectPosts = reduxState => reduxState.posts.myPost

操作：

export const addPosts = ({ subId, postId, userId, content }) => ({
  type: "posts/add",
  payload: {
    userId,
    postId,
    content,
    subId
  },
});

减速器：

const myPost = [],
      
  
  
export default function reducer(state = myPost, action) {
    switch (action.type) {
      case "posts/add": {
        return {
            
          ...state,
          myPost: [
            ...state.posts,
            {
              userId: action.payload.userId,            
              postId: action.payload.postId,
              content: action.payload.content,
              subId: action.payload.subId,
              
            },
          ],
        };
      }
      default: {
        return state;
      }
    }
  }

我用 const posts = useSelector(selectPosts);

调用选择器

我看了很多，虽然有很多问题与我的问题相同，但我一直没能取得任何进展。

我认为这可能与我阅读对象的方式有关，但我还没有解决

谢谢

塞缪尔-png

编辑：我收到的错误如下：

TypeError: Cannot read property 'myPost' of undefined

selectPosts
src/store/posts/selectors.js:1
> 1 | export const selectPosts = reduxState => reduxState.post.myPost
View compiled

▶ 2 stack frames were collapsed.

FrontPage
src/pages/FrontPage.js:10
   7 | import { useDispatch } from "react-redux";
   8 | 
   9 | export default function FrontPage() { 
> 10 | const posts = useSelector(selectPosts);
  11 | console.log(posts)
  12 |   return (
  13 |     <div>

还有商店

import userReducer from "./user/reducer";
import postReducer from "../posts/reducer";

import { createStore, applyMiddleware, compose, combineReducers } from "redux";
import ReduxThunk from "redux-thunk";

const devTools = window.__REDUX_DEVTOOLS_EXTENSION__
  ? window.__REDUX_DEVTOOLS_EXTENSION__()
  : (x) => x;

const enhancer = compose(applyMiddleware(ReduxThunk), devTools);
const store = createStore(
  combineReducers({
    user: userReducer,
    team: postReducer,
  }),
  enhancer
);

export default store;

Answer 1

您正在将您的帖子映射到 combineReducers 中的团队，因此您必须通过该键在 useSelectors 中进行引用。
const posts = useSelector(state => state.team) 也不要更改传递给减速器的 initialState 的类型您的帖子减速器中的示例，您正在传递一个数组 myPost 作为 initialState 但是稍后从减速器返回一个对象，这可能会带来更多错误。

Redux 状态变为未定义

1 个答案: