What does Persist Redux state mean?

One common challenge in React applications is rehydrating the Redux state after a page reload or between user sessions. A typical workaround is to re-fetch the data via an API call and store it in the Redux state. However, you can now rehydrate the Redux state without additional API calls using a technique called Persisted Redux State.

The `redux-persist` package

This package and the typical redux packages @reduxjs/toolkit and react-redux can be used to create a redux state that can persist across the page reload or user session in the browser.

Prerequisites

You have a running react application.

Installations

Use this command to install all the necessary packages to set up a persisting redux state.

npm i --save @reduxjs/toolkit react-redux redux-persist

Setting up a Persisting Redux State

1.Configure your redux store [store.js].

import { combineReducers, configureStore } from "@reduxjs/toolkit";
import sampleSlice from "./sampleSlice";
import storageSession from "redux-persist/lib/storage/session"; // session storage
import { FLUSH, PAUSE, PERSIST, persistReducer, persistStore, PURGE, REGISTER, REHYDRATE } from 'redux-persist';

const rootReducer = combineReducers({
     sample : sampleSlice.reducer;
})
const persistConfig = {
     key:'root',
     storage: storageSession,
}
const persistedReducer = persistReducer(persistConfig, rootReducer)
const store = configureStore({
     reducer: persistedReducer,
     middleware: (getDefaultMiddleware) => 
               getDefaultMiddleware({
                   serializableCheck: {
                         ignoredActions: [FLUSH, REHYDRATE, PAUSE, PERSIST, PURGE, REGISTER],
           },
     }) 
})
const persister = persistStore(store);
export default store

NOTE: If you want your redux to persist not only between the reloads but also between the user-sessions in the browser replace the

import storageSession from "redux-persist/lib/storage/session"; // session storage

import with

import storageSession from "redux-persist/lib/storage"; // local storage

2.Wrap your Root Component [index.js].

import React from 'react';
import ReactDOM from 'react-dom/client';
import './index.css';
import { BrowserRouter } from 'react-router-dom';
import store, { persistor } from './store';
import { Provider } from 'react-redux';
import { PersistGate } from 'redux-persist/integration/react';
import App from './App';

const root = ReactDOM.createRoot(document.getElementById('root') as HTMLElement);
root.render(<BrowserRouter>
    <Provider store={store}>
        <PersistGate loading={null} persistor={persistor}>
            <App />
        </PersistGate>
    </Provider>
</BrowserRouter>);

and done! your persisting redux state is ready.

Persist Redux State

What does Persist Redux state mean?

The redux-persist package

Prerequisites

Installations

Setting up a Persisting Redux State

The `redux-persist` package