React notify message without refresh page
Published: 2023-10-30 08:08:48

To send notifications to your website without refreshing the page in a React application, you can use various methods and libraries, but one of the most popular and straightforward options is to use a library like `react-toastify`. `react-toastify` allows you to easily display notifications or toasts in your React application without requiring a page refresh.

Here's a step-by-step guide on how to implement notifications using `react-toastify`:

1. **Create a React App**: If you don't already have a React application, you can create one using tools like Create React App:

   ```bash
   npx create-react-app my-notification-app
   cd my-notification-app
   ```

2. **Install `react-toastify`**: Install the `react-toastify` library by running the following command:

   ```bash
   npm install react-toastify
   ```

3. **Import and Set Up `react-toastify`**: In your main application file (usually `src/index.js` or `src/App.js`), import and configure `react-toastify`:

   ```jsx
   import React from 'react';
   import ReactDOM from 'react-dom';
   import { ToastContainer } from 'react-toastify';
   import 'react-toastify/dist/ReactToastify.css';
   import App from './App';

   ReactDOM.render(
     <React.StrictMode>
       <App />
       <ToastContainer /> {/* Add this line to enable toasts */}
     </React.StrictMode>,
     document.getElementById('root')
   );
   ```

4. **Display Notifications**: In your component where you want to display notifications, you can use the `toast` method from `react-toastify`:

   ```jsx
   import React from 'react';
   import { toast } from 'react-toastify';

   function MyComponent() {
     const notify = () => {
       toast('Notification message here');
     };

     return (
       <div>
         <button onClick={notify}>Show Notification</button>
       </div>
     );
   }

   export default MyComponent;
   ```

5. **Customize Notifications**: You can customize the appearance and behavior of notifications by passing options to the `toast` function. For example:

   ```jsx
   import React from 'react';
   import { toast } from 'react-toastify';

   function MyComponent() {
     const notify = () => {
       toast.success('Success message', {
         position: toast.POSITION.TOP_RIGHT,
         autoClose: 3000, // Close after 3 seconds
       });
     };

     return (
       <div>
         <button onClick={notify}>Show Notification</button>
       </div>
     );
   }

   export default MyComponent;
   ```

6. **Styling**: You can also apply custom styling to your notifications by modifying the CSS or using the provided CSS classes in your stylesheet.

7. **Managing Different Types of Notifications**: `react-toastify` provides different methods for displaying different types of notifications like success, error, warning, etc., as shown in the example above with `toast.success`.

8. **Handle Click Events**: You can add onClick handlers to your notifications to perform actions when a user clicks on them.

By following these steps, you can easily integrate notifications into your React application without the need to refresh the page.

## Backend by spring-boot what subcribe an kakfa topic for notify

To subscribe to a Kafka topic in a Spring Boot application and send notifications to your frontend when new messages arrive in the Kafka topic, you can follow these steps:

1. **Set up Kafka in your Spring Boot application**:
   
   First, make sure you have Kafka set up in your Spring Boot project. You'll need to configure Kafka properties in your `application.properties` or `application.yml` file. Here's a minimal example of `application.properties`:

   ```properties
   spring.kafka.consumer.bootstrap-servers=localhost:9092
   spring.kafka.consumer.group-id=my-group
   spring.kafka.consumer.auto-offset-reset=earliest
   ```

2. **Create a Kafka Consumer**:

   Create a Kafka consumer to subscribe to the Kafka topic and process incoming messages. You can use the Spring Kafka library for this. Here's an example:

   ```java
   import org.apache.kafka.clients.consumer.ConsumerConfig;
   import org.apache.kafka.clients.consumer.ConsumerRecord;
   import org.springframework.kafka.annotation.KafkaListener;
   import org.springframework.kafka.core.ConsumerFactory;
   import org.springframework.kafka.core.DefaultKafkaConsumerFactory;
   import org.springframework.kafka.listener.ConcurrentMessageListenerContainer;
   import org.springframework.kafka.listener.config.ContainerProperties;
   import org.springframework.kafka.support.serializer.ErrorHandlingDeserializer;
   import org.springframework.kafka.support.serializer.JsonDeserializer;
   import org.springframework.kafka.support.serializer.JsonSerializer;
   import org.springframework.stereotype.Service;

   import java.util.HashMap;
   import java.util.Map;

   @Service
   public class KafkaConsumerService {
       private final String kafkaTopic = "your-topic-name"; // Replace with your Kafka topic name

       @KafkaListener(topics = kafkaTopic, groupId = "my-group")
       public void listen(ConsumerRecord<String, String> record) {
           // Process the incoming Kafka message here
           String message = record.value();
           // Send the message to your frontend (e.g., via WebSocket or an API)
       }
   }
   ```

3. **Send Notifications to Frontend**:

   Inside the `listen` method of your Kafka consumer, you can send notifications to your frontend. How you send notifications will depend on your frontend technology. Here are a few options:

   - **WebSocket**: If your frontend uses WebSocket, you can send notifications in real-time to connected clients when Kafka messages arrive. You'll need to set up WebSocket support in your Spring Boot application and establish WebSocket connections from your frontend.

   - **REST API**: You can expose a REST API endpoint in your Spring Boot application that your frontend can poll to check for new notifications. When a Kafka message arrives, you can add it to a queue or database, and the API can fetch the latest notifications when requested by the frontend.

   - **Server-Sent Events (SSE)**: SSE is a simple and efficient way to send notifications from the server to the client over a single HTTP connection. You can create an SSE endpoint in your Spring Boot application and use it to send Kafka messages as events to the connected clients.

4. **Frontend Integration**:

   Depending on the method you choose to send notifications to the frontend, you'll need to integrate WebSocket, REST API, or SSE handling in your frontend code to receive and display notifications to users.

Remember to handle error scenarios, retries, and other production-level concerns when implementing this in a real-world application. Additionally, you should secure your Kafka cluster and API endpoints to ensure data integrity and user authentication as needed.

How react receive above notification?
In a React application, you can receive notifications from the backend (e.g., via WebSocket, REST API, SSE) and display them to the user. Below, I'll provide a basic example using WebSocket for real-time notifications.

1. **Set Up WebSocket in Your React App**:

   You'll need a WebSocket library to establish a connection with the server. One popular library is `socket.io-client`. Install it using:

   ```bash
   npm install socket.io-client
   ```

2. **Create a WebSocket Connection**:

   In your React component, establish a WebSocket connection to the backend. For example, you can create a `WebSocketProvider` component to manage the WebSocket connection:

   ```jsx
   // WebSocketProvider.js
   import React, { createContext, useContext, useEffect, useState } from 'react';
   import io from 'socket.io-client';

   const WebSocketContext = createContext();

   export function useWebSocket() {
     return useContext(WebSocketContext);
   }

   export function WebSocketProvider({ children }) {
     const [socket, setSocket] = useState(null);

     useEffect(() => {
       const newSocket = io('http://your-backend-url'); // Replace with your backend WebSocket URL
       setSocket(newSocket);

       return () => {
         newSocket.close();
       };
     }, []);

     return (
       <WebSocketContext.Provider value={socket}>
         {children}
       </WebSocketContext.Provider>
     );
   }
   ```

3. **Use the WebSocket Connection to Receive Notifications**:

   Now, you can use the `useWebSocket` hook to access the WebSocket connection in your components and listen for incoming notifications. For example:

   ```jsx
   // NotificationComponent.js
   import React, { useEffect } from 'react';
   import { useWebSocket } from './WebSocketProvider';

   function NotificationComponent() {
     const socket = useWebSocket();

     useEffect(() => {
       if (socket) {
         socket.on('notification', (data) => {
           // Handle the incoming notification data and display it to the user
           console.log('Received notification:', data);
         });
       }
     }, [socket]);

     return (
       <div>
         {/* Render notifications here */}
       </div>
     );
   }

   export default NotificationComponent;
   ```

4. **Send Notifications from the Backend**:

   In your backend (e.g., Spring Boot application), when an event occurs that should trigger a notification, you can use the WebSocket connection to send data to connected clients. For example, using the `socket.io` library in Node.js:

   ```javascript
   // In your Node.js backend
   const io = require('socket.io')(server); // 'server' is your HTTP server instance

   // Handle WebSocket connections
   io.on('connection', (socket) => {
     console.log('A user connected');
     
     // When an event occurs that should trigger a notification
     socket.emit('notification', { message: 'New notification' });

     // Handle disconnections
     socket.on('disconnect', () => {
       console.log('A user disconnected');
     });
   });
   ```

5. **Rendering Notifications**:

   Inside your `NotificationComponent`, you can render the notifications in a user-friendly manner, such as using a notification library like `react-toastify` as mentioned earlier in this conversation or by creating a custom notification component.

This setup establishes a WebSocket connection between your React frontend and your backend server. When the backend sends a notification event, the React component will receive it and can take appropriate action to display the notification to the user. You can customize the notification rendering and handling based on your application's requirements.

## Use case of RestAPI

Using a REST API to receive notifications from a backend in a React application is a common approach. Here's a step-by-step example of how to implement this:

1. **Set Up Your Backend with REST API**:

   Your Spring Boot backend should expose a REST API endpoint that your React frontend can call to check for new notifications. For this example, let's assume you have an endpoint `/api/notifications` that returns a list of notifications.

   ```java
   // NotificationController.java in your Spring Boot application
   @RestController
   @RequestMapping("/api/notifications")
   public class NotificationController {

       @GetMapping
       public List<Notification> getNotifications() {
           // Retrieve and return notifications from your database or another source
           List<Notification> notifications = ...; // Fetch notifications
           return notifications;
       }
   }
   ```

2. **Fetch Notifications in React**:

   In your React component, you can use the `fetch` or a library like `axios` to make an HTTP GET request to your backend's `/api/notifications` endpoint to retrieve notifications.

   ```jsx
   // NotificationComponent.js in your React app
   import React, { useEffect, useState } from 'react';
   import axios from 'axios';

   function NotificationComponent() {
     const [notifications, setNotifications] = useState([]);

     useEffect(() => {
       async function fetchNotifications() {
         try {
           const response = await axios.get('/api/notifications');
           setNotifications(response.data);
         } catch (error) {
           console.error('Error fetching notifications:', error);
         }
       }

       fetchNotifications();
     }, []);

     return (
       <div>
         <h2>Notifications</h2>
         <ul>
           {notifications.map((notification) => (
             <li key={notification.id}>{notification.message}</li>
           ))}
         </ul>
       </div>
     );
   }

   export default NotificationComponent;
   ```

3. **Display Notifications**:

   The fetched notifications are stored in the `notifications` state variable and displayed in your component. This example assumes you have a list of notifications with a `message` field.

4. **Poll for New Notifications**:

   To continuously check for new notifications, you can use `setInterval` or a library like `setTimeout` to periodically make requests to the `/api/notifications` endpoint. Be cautious about setting the polling interval to avoid excessive requests to your server.

   ```jsx
   useEffect(() => {
     const pollingInterval = 5000; // Poll every 5 seconds (adjust as needed)

     const fetchNotifications = async () => {
       try {
         const response = await axios.get('/api/notifications');
         setNotifications(response.data);
       } catch (error) {
         console.error('Error fetching notifications:', error);
       }
     };

     const intervalId = setInterval(fetchNotifications, pollingInterval);

     // Cleanup when the component unmounts
     return () => clearInterval(intervalId);
   }, []);
   ```

5. **Error Handling and Optimization**:

   Ensure you handle errors and optimize your REST API for efficiency. You can use pagination or other techniques to avoid retrieving all notifications in a single request if you have a large number of notifications.

This approach allows your React frontend to periodically check for new notifications from your Spring Boot backend via a REST API. You can customize the polling interval and notification rendering based on your application's requirements.

## Use case for SSE

To receive notifications from your Spring Boot backend to your React frontend using Server-Sent Events (SSE), you can follow these steps:

1. **Set Up SSE in Your Spring Boot Application**:

   First, create an SSE endpoint in your Spring Boot application. You can use the `SseEmitter` class provided by Spring to stream events to clients. Here's a basic example:

   ```java
   import org.springframework.web.bind.annotation.GetMapping;
   import org.springframework.web.bind.annotation.RequestMapping;
   import org.springframework.web.bind.annotation.RestController;
   import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;

   import java.util.concurrent.CopyOnWriteArrayList;

   @RestController
   @RequestMapping("/sse")
   public class SseController {
       private final CopyOnWriteArrayList<SseEmitter> emitters = new CopyOnWriteArrayList<>();

       @GetMapping("/notifications")
       public SseEmitter getNotifications() {
           SseEmitter emitter = new SseEmitter();
           emitters.add(emitter);

           emitter.onTimeout(() -> {
               emitter.complete();
               emitters.remove(emitter);
           });

           emitter.onCompletion(() -> emitters.remove(emitter));

           return emitter;
       }

       public void sendNotification(String message) {
           emitters.forEach(emitter -> {
               try {
                   emitter.send(SseEmitter.event().data(message));
               } catch (Exception e) {
                   emitter.complete();
                   emitters.remove(emitter);
               }
           });
       }
   }
   ```

2. **Send Notifications from the Backend**:

   In your Spring Boot backend, you can send notifications to connected SSE clients by calling the `sendNotification` method from your controller. For example:

   ```java
   // Inject the SseController into your service or controller
   @Autowired
   private SseController sseController;

   public void sendNotificationToClients(String message) {
       sseController.sendNotification(message);
   }
   ```

3. **Set Up SSE in Your React Application**:

   Create a React component to connect to the SSE endpoint and receive notifications. You can use the `EventSource` API provided by browsers for SSE communication. Here's an example component:

   ```jsx
   import React, { useEffect, useState } from 'react';

   function SseNotificationComponent() {
       const [notifications, setNotifications] = useState([]);

       useEffect(() => {
           const eventSource = new EventSource('/sse/notifications');

           eventSource.onmessage = (event) => {
               const newNotification = event.data;
               setNotifications((prevNotifications) => [...prevNotifications, newNotification]);
           };

           eventSource.onerror = (error) => {
               console.error('SSE Error:', error);
               eventSource.close();
           };

           return () => {
               eventSource.close();
           };
       }, []);

       return (
           <div>
               <h2>Server-Sent Events Notifications</h2>
               <ul>
                   {notifications.map((notification, index) => (
                       <li key={index}>{notification}</li>
                   ))}
               </ul>
           </div>
       );
   }

   export default SseNotificationComponent;
   ```

4. **Display Notifications**:

   Notifications received through SSE are stored in the `notifications` state variable and displayed in your React component.

With this setup, your React frontend will establish an SSE connection to your Spring Boot backend's `/sse/notifications` endpoint. When the backend sends a notification event, the React component will receive it and display it in real-time. SSE is an efficient way to push notifications from the server to the client without the need for constant polling.