Redux Persist: Complete Guide to State Persistence in React Applications

Storing and Persisting Redux Toolkit States with Redux Persist

Introduction
Key Benefits
Implementation Guide
Store Configuration
Application Integration
Important Points
Frequently Asked Questions

Introduction

Redux Persist is a powerful library that enables state persistence in Redux applications. It automatically saves your Redux store to storage (like localStorage) and rehydrates it when the application restarts, ensuring your application maintains its state even after page refreshes or browser restarts.

Key Benefits

Maintains application state across page refreshes
Preserves user data between sessions
Seamless integration with Redux Toolkit
Configurable storage options

Implementation Guide

Prerequisites

npm install redux-persist

Configuration of Redux Toolkit with State in the Application

If you haven’t done that, don’t worry! Just follow my previous blog on the topic: Understanding Redux Toolkit: Global State Management in React 🙏 Namaste React .

Store Configuration ( redux/store.js )

import { combineReducers, configureStore } from '@reduxjs/toolkit';
import { persistReducer, persistStore } from 'redux-persist';
import storage from 'redux-persist/lib/storage';

const rootReducer = combineReducers({
    user: userReducer,
});

const persistConfig = {
    key: 'root',
    storage,
    version: 1,
};

const persistedReducer = persistReducer(persistConfig, rootReducer);

Application Integration ( main .jsx )

            
import { createRoot } from 'react-dom/client'
import { Provider } from 'react-redux'
import './index.css'
import App from './App.jsx'
import {store,persistor} from './redux/store.js'
import { PersistGate } from 'redux-persist/integration/react'


createRoot(document.getElementById('root')).render(
  <PersistGate persistor={persistor}>
    <Provider store={store}>
        <App />
    </Provider>
</PersistGate>
)

Important Points

State persistence occurs automatically after setup
Data persists until explicitly cleared
Configure which reducers to persist using whitelist/blacklist
Ideal for maintaining user sessions and preferences
After page is rerfresh the presists rehydrate store the state conentent automatically.

View Code on GitHub (Check Redux Persist Commits)

Core Concepts Explained

1. Why do we need to combine reducers in Redux Persist?

Combining reducers is essential in Redux Persist for several reasons:

It allows us to organize different parts of our application state into separate reducers.
Makes the code more maintainable by splitting state management logic.
Enables selective persistence through whitelist/blacklist configuration.
Helps in scaling the application by keeping state management modular.

2. Why do we need middleware configuration in Redux Persist?

Middleware configuration, particularly setting `serializableCheck` to false, is crucial because:

Redux Persist needs to handle non-serializable values during the persistence process.
It prevents warnings about non-serializable values in the Redux store.
Allows Redux Persist to properly handle the rehydration process.
Enables smooth integration with the storage engine.

3. What is the purpose of PersistGate in Redux Persist?

PersistGate is a crucial component that serves multiple purposes:

Delays the rendering of your app's UI until the persisted state has been retrieved and saved to Redux.
Prevents any race conditions between the persisted state and your app's initial render.
Ensures your app doesn't show stale or incorrect data during the rehydration process.
Provides a `loading` prop to show loading states while state is being restored.