Build a React.js Streaming Chat App with Langchain Integration

In this tutorial, we will walk you through the process of creating a streaming chat application using React.js and integrating it with the Langchain API to facilitate real-time translation, providing users with a seamless communication experience.

Table of Contents

1. Prerequisites
2. Setting Up the Project
3. Creating the Chat Interface
4. Integrating Langchain API
5. Adding Real-Time Translation
6. Testing the Application
7. Conclusion

Prerequisites

Before starting, make sure you have the following installed:

• Node.js (version 14.x or higher)
• npm (version 7.x or higher)
• A code editor like Visual Studio Code

Setting Up the Project

1. Create a new React.js project using create-react-app:

   npx create-react-app streaming-chat-app
   cd streaming-chat-app
   

2. Install dependencies:

   npm install axios react-chat-engine
   

Creating the Chat Interface

1. Replace the contents of src/App.js with the following code:

   import { ChatEngine } from 'react-chat-engine';
   import './App.css';
   
   function App() {
     return (
       <div className="App">
         <ChatEngine
           height="100vh"
           userName="Your_Username"
           userSecret="Your_User_Secret"
           projectID="Your_Project_ID"
         />
       </div>
     );
   }
   
   export default App;
   

   Replace Your_Username, Your_User_Secret, and Your_Project_ID with your credentials from the ChatEngine dashboard.

2. Update the src/App.css file with your desired styling.

Integrating Langchain API

1. Sign up for a free Langchain API account and obtain your API key.

2. Create a new file called src/langchainAPI.js and add the following code:

   import axios from 'axios';
   
   const instance = axios.create({
     baseURL: 'https://api.langchain.io/',
     headers: {
       'Authorization': `Bearer YOUR_LANGCHAIN_API_KEY`
     }
   });
   
   export default instance;
   

   Replace YOUR_LANGCHAIN_API_KEY with your actual Langchain API key.

Adding Real-Time Translation

1. Create a new file called src/translateMessage.js and add the following code:

   import langchainAPI from './langchainAPI';
   
   async function translateMessage(text, targetLanguage) {
     try {
       const response = await langchainAPI.post('/translate', {
         q: text,
         target: targetLanguage
       });
       return response.data.translatedText;
     } catch (error) {
       console.error('Error translating message:', error);
       return text;
     }
   }
   
   export default translateMessage;
   

2. Modify the src/App.js file to include translation functionality:

   import { useState, useEffect } from 'react';
   import { ChatEngine } from 'react-chat-engine';
   import translateMessage from './translateMessage';
   import './App.css';
   
   function App() {
     const [language, setLanguage] = useState('en');
   
     useEffect(() => {
       const handleMessageTranslate = async (data) => {
         const translatedText = await translateMessage(data.text, language);
         data.text = translatedText;
       };
   
       ChatEngine.prototype.onAny((event_type, data) => {
         if (event_type === 'message_created') {
           handleMessageTranslate(data);
         }
       });
     }, [language]);
   
     return (
       <div className="App">
         <ChatEngine
           height="100vh"
           userName="Your_Username"
           userSecret="Your_User_Secret"
           projectID="Your_Project_ID"
         />
       </div>
     );
   }
   
   export default App;
   

   This code adds an event listener for new messages and translates them using the translateMessage function.

Testing the Application

1. Run the development server:

   npm start
   

2. Open your browser and navigate to http://localhost:3000/.

3. Test the chat functionality and translation features.

Conclusion

Congratulations! You have successfully built a React.js streaming chat application with Langchain integration. Users can now communicate seamlessly using real-time translation. Feel free to further customize the application and add additional features as needed.