ReduxToolkit useSelector Hook：通过 useDispatch 更新选定的 redux-state 后，React 功能组件不会重新渲染

Question

我正在开发一个测验游戏，我希望 SingleChoice 组件从 QuizApi 获取 SingleChoice 问题。 当用户单击开始按钮时，要播放 singleQuestionMode，组件应该获取问题并将它们显示在屏幕上（出于测试目的，我只是显示了一个 ,,hello" 文本）。然后开始按钮应该消失（点击后）。

为了实现这一点，我创建了一个名为 gameStarted 的 redux 状态，它是一个布尔值。 我使用 useSelector() 来导入组件内部的状态，并为组件订阅该状态的状态更改。 在 return 语句中，我使用 {} 注入了一个三元运算符，该运算符呈现按钮（如果游戏尚未开始，也就是 gameStarted-state 等于 false），它呈现 ,,hello" 文本并让按钮在用户消失时消失单击按钮以启动 SingleQuestionsMode（又名 gameStarted 已设置为 true）。

但是，如果我单击开始按钮，我可以在浏览器的 devConsole 中看到，问题被正确获取，并且通过 redux-devtools 我可以看到 gameStarted redux 状态正确设置为 true（最初为 false），但仍然组件不重新呈现（不显示“hello”-占位符并且按钮不消失）。

浏览器中开发控制台的屏幕截图：单击按钮之前：单击按钮之前

单击按钮后：单击按钮后

这是为什么？ 即使我最初将 gameStarted redux-state 设置为 true，它也会显示 ,,hello"- 占位符文本而不是按钮。所以这一切似乎都设置正确，但在 gameStarted redux 状态更改后，有些东西会阻止重新渲染。也许我也使用过 redux-persist？

以下是所有相关代码：

SingleChoice.js 代码：

import React, { useEffect, useState} from 'react';
import {useSelector, useDispatch} from 'react-redux';
import {selectGameStatus, setGameStarted} from "../loginSlice";

export default function SingleChoice() {
    const dispatch = useDispatch();
    const [questions, setQuestions] = useState([]);

    const gameStarted = useSelector(selectGameStatus);
    
    const fetchSingleQuestions = async () => {
        const questionData = await fetch('url-here');
        const questions = await questionData.json();
        setQuestions(questions.results)
        console.log(questions.results);
    }

    const startGame = () => {
        fetchSingleQuestions();
        dispatch(setGameStarted());
    }
     

    return (
        <div>
            <h1>SingleChoiceMode</h1>
            {!gameStarted ? <button onClick={startGame}>Spiel starten</button> : <div><h1>Hello</h1></div>}
        </div>
    )
}

具有上述 gameStarted 状态的切片代码：

import { createAsyncThunk, createSlice } from '@reduxjs/toolkit';


const initialState = {
    loggedIn: false,
    accountInfo: {
        id: "",
        username: "",
        mail: "", 
        password: "",
        singlescore: "", 
        multiscore: "", 
        mixedscore: ""
    },
    gameStarted: false
};
export const LoginSlice = createSlice({

    name: 'login',
    initialState,
    reducers: {
        setLoginTrue: (state) => {
            state.loggedIn = true;
        },
        setLoginFalse: (state) => {
            state.loggedIn = false;
        },
        setAccountInfo: (state, action) => {
            state.accountInfo = {
                id: action.payload.id,
                username: action.payload.username,
                mail: action.payload.mail,
                password: action.payload.password,
                singlescore: action.payload.singlescore,
                multiscore: action.payload.multiscore,
                mixedscore: action.payload.mixedscore
            }
        },
        setGameStarted: (state) => {
            state.gameStarted = true;
        },
        setGameStopped: (state) => {
            state.gameStarted = false;
        }
    }
});

export const selectLoginState = (state) => state.login.loggedIn;
export const selectAccountInfo = (state) => state.login.accountInfo;
export const selectGameStatus = (state) => state.gameStarted;
export const { setLoginTrue, setLoginFalse, setAccountInfo, setGameStarted, setGameStopped } = LoginSlice.actions;
export default LoginSlice.reducer;

redux-store 的代码（我也使用 redux-persist 来保持用户登录）：

import { configureStore } from '@reduxjs/toolkit';
import loginReducer from '../features/loginSlice';
import storage from "redux-persist/lib/storage";
import {combineReducers} from "redux"; 
import { persistReducer } from 'redux-persist'

const reducers = combineReducers({
  login: loginReducer
})

const persistConfig = {
  key: 'root',
  storage
};

const persistedReducer = persistReducer(persistConfig, reducers);


const store = configureStore({
  reducer: persistedReducer,
  devTools: process.env.NODE_ENV !== 'production'
});

export default store;

Index.js 的代码：

ReactDOM.render(
  <React.StrictMode>
    <BrowserRouter>
      <Provider store={store}>
        <PersistGate loading={null} persistor={persistor}>
          <App />
        </PersistGate>
      </Provider>
    </BrowserRouter>
  </React.StrictMode>,
  document.getElementById('root')
);

路由和渲染所有内容的组件 App.js 的代码

import React from 'react';
import Home from "./features/Home";
import SingleChoice from "./features/modes/SingleChoice"
import MultipleChoice from "./features/modes/MultipleChoice"
import Mixed from "./features/modes/Mixed"
import Login from "./features/Login"
import Profile from "./features/Profile"
import Rankings from "./features/Rankings"
import NotFound from "./features/NotFound"
import Register from "./features/Register"
import Protected from "./features/Protected"
import { NavBar } from "./features/Navbar";
import './App.css';
import { Routes, Route } from "react-router-dom";

function App() {

  return (
    <div className="App">
      <NavBar />
      <Routes>
        <Route path="/" element={<Home />} />
        <Route element={<Protected />}>
          <Route path="/single" element={<SingleChoice />} />
          <Route path="/multiple" element={<MultipleChoice />} />
          <Route path="/mixed" element={<Mixed />} />
          <Route path="/profile" element={<Profile />} />
          <Route path="/rankings" element={<Rankings />} />
        </Route>
        <Route path="/login" element={<Login />} />
        <Route path="/register" element={<Register />} />
        <Route path="*" element={<NotFound />} />
      </Routes>
    </div>
  );
}

export default App;

请帮助我，以便 SingleChoice 组件在导入的 redux-state 发生更改后最终重新渲染。

Answer 1

在SingleChoice.js中，而不是

const gameStarted = useSelector(selectGameStatus);

    ...

const startGame = () => {
    fetchSingleQuestions();
    dispatch(setGameStarted());
}

类型 ：

const { gameStarted } = useSelector((state) => state.login);

...

const startGame = () => {
    fetchSingleQuestions();
    dispatch(setGameStarted(true));
}

---

在loginSlice.js 中替换

setGameStarted: (state) => {
    state.gameStarted = true;
},

经过 ：

setGameStarted: (state, action) => {
    state.gameStarted = action.payload;
},

演示： Stackblitz