Batching Multiple REST API Requests in a Single Call (Backend Proxy)

// server.js (using Express)
const express = require('express');
const axios = require('axios');
const app = express();
const PORT = 3000;

app.use(express.json()); // Middleware to parse JSON bodies

// Example client-side request structure for batching
/*
[
  { "method": "GET", "path": "/users/1" },
  { "method": "GET", "path": "/products?limit=5" },
  { "method": "POST", "path": "/analytics", "body": { "event": "page_view", "page": "/dashboard" } }
]
*/

app.post('/batch', async (req, res) => {
  const requests = req.body; // Array of request objects from client
  if (!Array.isArray(requests) || requests.length === 0) {
    return res.status(400).json({ error: 'Request body must be an array of API requests.' });
  }

  const results = await Promise.all(
    requests.map(async (request) => {
      const { method, path, body } = request;
      const targetUrl = `https://api.example.com${path}`; // Replace with your actual target API base URL

      try {
        const apiResponse = await axios({
          method: method || 'GET',
          url: targetUrl,
          data: body, // For POST/PUT requests
          headers: {
            // Add any necessary headers for your target API (e.g., Authorization)
            // 'Authorization': `Bearer ${process.env.API_KEY}`
          }
        });
        return { status: apiResponse.status, data: apiResponse.data, success: true };
      } catch (error) {
        // console.error(`Error processing batched request to ${targetUrl}:`, error.message);
        return {
          status: error.response ? error.response.status : 500,
          data: error.response ? error.response.data : { message: 'Internal proxy error' },
          success: false,
          request: { method, path } // Include original request for context
        };
      }
    })
  );

  res.json(results);
});

app.listen(PORT, () => {
  console.log(`Batch API proxy listening on http://localhost:${PORT}`);
});

// Client-side usage example (e.g., with Axios)
/*
// const clientRequests = [
//   { method: 'GET', path: '/users/1' },
//   { method: 'GET', path: '/products?limit=2' }
// ];
//
// axios.post('http://localhost:3000/batch', clientRequests)
//   .then(response => {
//     console.log('Batch results:', response.data);
//     // response.data will be an array like:
//     // [
//     //   { status: 200, data: { ...user1 }, success: true },
//     //   { status: 200, data: [ ...products ], success: true }
//     // ]
//   })
//   .catch(error => console.error('Batch request failed:', error));
*/