useDispatch() Error: Could not find react-redux context value; please ensure the component is wrapped in a <Provider>

Question

I am trygin to use React-Redux library and I am getting the error on the title. I wrapped my components with Provider but I still get the error, only if I implement the useDispatch() hook.

The app worked fine, until I added the useDispatch() line. The rest of lines regarding the dispatch function can be removed and I still get the same error.

If you could help me I would really appreciate it. Thanks

Here is my code:

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 must be wrapped in provider since you are using useDispatch in it. Right now it's just a child. Provider sets the context so only its children can have access to it, not a parent.

One solution would be to create a wrapper component for it:

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!
...

Answer 2

maybe you imported Provider into the App.js file. Provider needs to be imported into the file index.js.

/*index.js*/
import React from 'react';
import ReactDOM from 'react-dom';
import { Provider } from 'react-redux';
import { store } from './store/reduxStore';
import './index.css';
import App from './App';
import reportWebVitals from './reportWebVitals';

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

Answer 3

I did this on the same index.js file for a react-native app. This way you avoid having to export and add another file just for giving wrapping the App with the provider.

const ReduxProvider = () => {
    return(
        <Provider store={store}>
            <App />
        </Provider>
    )
}

AppRegistry.registerComponent(appName, () => ReduxProvider);

Answer 4

Happened to me, when I was calling React component as a function, without using it as virtual dom, Comp was independently called not rendered as child of some element

function Comp() {
  const a = useSelector(selectA); // throws error
}
Comp();

so in my case solution was to call Comp and a component, not as a function i.e <Comp />

Answer 5

Just type this in the beginning of project:

npx create-react-app app_name --template redux