Practical Use Cases

Custom middlewares can be used for various purposes in React Redux applications. Some common use cases include:

Authentication: Middleware can intercept actions related to user authentication, validate tokens, and handle authentication flows.
Logging: As demonstrated above, middleware can log actions, state changes, or any other relevant information for debugging purposes.
Asynchronous Operations: Middleware can handle asynchronous actions such as making API requests, dispatching multiple actions based on the result, or handling errors.
Caching: Middleware can implement caching mechanisms to optimize performance by storing frequently accessed data locally.

Example: Below are the example to create custom middleware in React Redux.

Install the necessary package in your application using the following command.

npm install react-redux redux

Javascript

// App.js
import React, { useEffect } from 'react';
import { connect } from 'react-redux';
import { fetchUsersRequest }
    from './actions/userAction';
 
const App = ({ users, loading, error, fetchUsers }) => {
    useEffect(() => {
        fetchUsers();
    }, [fetchUsers]);
 
    if (loading) {
        return <div>Loading...</div>;
    }
 
    if (error) {
        return <div>Error: {error}</div>;
    }
 
    if (!users || users.length === 0) {
        return <div>No users found</div>;
    }
 
    return (
        <div>
            <h1>Users</h1>
            <ul>
 
                {users.map(user => {
                    return (
                        <li key={user.id}>{user.name}</li>
                    );
                })}
 
            </ul>
        </div>
    );
};
 
const mapStateToProps = state => {
 
    return {
        users: state.users || [],
        loading: state.loading,
        error: state.error
    };
};
 
const mapDispatchToProps = dispatch => ({
    fetchUsers: () => dispatch(fetchUsersRequest())
});
 
export default connect(mapStateToProps, mapDispatchToProps)(App);

Javascript

import React from 'react';
import { createRoot } from 'react-dom/client';
import { Provider } from 'react-redux';
import App from './App';
import store from './store';
 
const root = createRoot(document.getElementById('root'));
 
root.render(
  <Provider store={store}>
    <App />
  </Provider>
);

Javascript

// store.js
import { applyMiddleware, createStore } from 'redux';
import userReducer from './reducers/userReducer';
import apiMiddleware from './middleware/apiMiddleware';
 
const store = createStore(
    userReducer,
    applyMiddleware(apiMiddleware)
);
 
export default store;

Javascript

// src/middleware/apiMiddleware.js
const apiMiddleware = store => next => action => {
    if (action.type === 'FETCH_USERS_REQUEST') {
        // Dispatch a loading action
        store.dispatch({ type: 'FETCH_USERS_LOADING' });
        setTimeout(() => {
            const users = [
                { id: 1, name: 'Rahul' },
                { id: 2, name: 'Sandeep' },
                { id: 3, name: 'Summit' },
                { id: 4, name: 'Riya' },
                { id: 5, name: 'Eva' }
            ];
            store.dispatch({
                type: 'FETCH_USERS_SUCCESS',
                payload: users
            });
        }, 1000);
    }
 
    return next(action);
};
 
export default apiMiddleware;

Javascript

// src/actions/userActions.js
export const fetchUsersRequest = () => ({
    type: 'FETCH_USERS_REQUEST'
});
 
export const fetchUsersSuccess = users => ({
    type: 'FETCH_USERS_SUCCESS',
    payload: users
});
 
export const fetchUsersFailure = error => ({
    type: 'FETCH_USERS_FAILURE',
    payload: error
});

Javascript

// src/reducers/userReducer.js
 
const initialState = {
    users: [],
    loading: false,
    error: null
};
 
const userReducer = (state = initialState, action) => {
    switch (action.type) {
        case 'FETCH_USERS_REQUEST':
            return { ...state, loading: true };
        case 'FETCH_USERS_SUCCESS':
            return {
                ...state, loading: false,
                users: action.payload, error: null
            };
        case 'FETCH_USERS_FAILURE':
            return {
                ...state, loading: false,
                error: action.payload
            };
        default:
            return state;
    }
};
 
export default userReducer;

Start your application using the following command.

npm start

Output:

Output

Creating custom middlewares in React Redux

In React-Redux applications, managing the flow of data is crucial for building efficient and scalable apps. Redux provides a powerful state management solution, and custom middleware adds an extra layer of flexibility to handle complex scenarios effectively.

Let’s understand custom middleware in simpler terms and see how we can create and use them.

Table of Content

What is Middleware?
Creating Custom Middleware
Practical Use Cases

Tags:

#Redux #ReactJS #Web Technologies

Creating Custom Middleware:

Practical Use Cases

Javascript

Javascript

Javascript

Javascript

Javascript

Javascript

Creating custom middlewares in React Redux

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