reactjs - useDispatch()错误: Could not find react-redux context value; please ensure the component is wrapped in a

Question

我正在尝试使用 React-Redux 库，但在标题上出现错误。我用 Provider 包装了我的组件，但仅当我实现 useDispatch() Hook 时，我仍然收到错误。

应用程序运行良好，直到我添加了 useDispatch() 行。关于调度函数的其余行可以删除，但我仍然得到相同的错误。

如果您能帮助我，我将非常感激。谢谢

这是我的代码:

import 'react-native-gesture-handler';
import {NavigationContainer} from '@react-navigation/native';
import Navigator from './navigation/Navigator';

import React, {useEffect, useState, useCallback} from 'react';
import {SafeAreaView, StyleSheet, Text, View} from 'react-native';

import {createStore, combineReducers} from 'redux';
import {Provider, useDispatch} from 'react-redux';
import dataReducer from './store/reducers/dataReducer';
import {CONSTANTS} from './constants/constants';
import {saveInitialData} from './store/actions/dataActions';

const App = () => {
  const [fetched, setFetched] = useState(initialState);

  const dispatch = useDispatch();

  const saveInitialDataHandler = useCallback(data => {
    dispatch(saveInitialData(data));
    callback;
  }, []);

  const rootReducer = combineReducers({
    content: dataReducer,
  });

  const store = createStore(rootReducer);

  useEffect(() => {
    fetchData();
  }, []);

  const fetchData = () => {
    fetch(CONSTANTS.database)
      .then(response => response.json())
      .then(responseJSON => {
        setFetched(true);
        saveInitialDataHandler(responseJSON);
      });
  };

  if (!fetched) {
    return (
      <Provider store={store}>
        <View stlye={{flex: 1, alignItems: 'center', justifyContent: 'center'}}>
          <Text></Text>
        </View>
      </Provider>
    );
  } else {
    return (
      <Provider store={store}>
        <NavigationContainer>
          <SafeAreaView style={styles.SafeAreaView}>
            <Navigator></Navigator>
          </SafeAreaView>
        </NavigationContainer>
      </Provider>
    );
  }
};

const styles = StyleSheet.create({
  SafeAreaView: {flex: 1},
});

export default App;

Answer 1

App 必须包装在提供程序中，因为您在其中使用 useDispatch 。现在还只是个 child 。 Provider 设置上下文，以便只有其子级可以访问它，而父级则不能。

一种解决方案是为其创建一个包装组件:

const AppWrapper = () => {
  const store = createStore(rootReducer);

  return (
    <Provider store={store}> // Set context
      <App /> // Now App has access to context
    </Provider>
  )
}

const App = () => {
  const dispatch = useDispatch(); // Works!
...