Node.js Web Frameworks: Master Express, Routing, and Middleware Mechanics (Part 2)

const express = require('express');
const app = express();
const TARGET_PORT = 5000;

// Built-in middleware to automatically intercept and parse incoming application/json request payloads
app.use(express.json());

// Implementing a baseline health-check endpoint route
app.get('/api/v1/health', (req, res) => {
  console.log(`[${new Date().toLocaleTimeString()}] Health checkpoint pinged by client.`);
  
  res.status(200).json({
    status: "success",
    message: "Backend server cluster is live and fully operational.",
    timestamp: new Date().toISOString()
  });
});

app.listen(TARGET_PORT, () => {
  console.log(`====================================================`);
  console.log(`🚀 Server listening on network port: ${TARGET_PORT}`);
  console.log(`====================================================`);
});

const express = require('express');
const app = express();

app.use(express.json());

// 1. Custom Global Application-Level Middleware: System Traffic Logger
app.use((req, res, next) => {
  const systemTimestamp = new Date().toISOString();
  console.log(`[${systemTimestamp}] INBOUND LOG - Method: ${req.method} | Route Path: ${req.url}`);
  
  // Explicitly call next() to push execution to the subsequent controller in line
  next();
});

// 2. Custom Route-Specific Middleware: Guarding Protected Systems
function verifySecurityClearance(req, res, next) {
  const secureApiKey = req.headers['x-api-key'];
  
  if (!secureApiKey || secureApiKey !== "puneet_secret_token") {
    console.warn(`[${new Date().toLocaleTimeString()}] ⚠️ Security Exception: Access Denied.`);
    // Stop the assembly line immediately by delivering a terminal response packet
    return res.status(403).json({
      status: "fail",
      error: "Unauthorised Access. A valid system security key must be provided in headers."
    });
  }
  
  console.log("Security verification passed successfully. Passing thread control.");
  next();
}

// Applying the protection middleware selectively to this single route signature
app.get('/api/v1/secure-vault', verifySecurityClearance, (req, res) => {
  res.status(200).json({
    status: "success",
    data: "Welcome, Administrator Puneet Tiwari. The vault records are fully loaded."
  });
});

// 1. ISOLATED ROUTER CAPACTIY FILE: studentRouter.js
const express = require('express');
const router = express.Router();

// Mock database collection representing records typically found in engineering databases
const studentRecords = [
  { rollNumber: "101", name: "Puneet Tiwari", department: "Computer Science", averageGpa: 9.6 },
  { rollNumber: "105", name: "Ananya Sharma", department: "Data Engineering", averageGpa: 9.1 }
];

// Route A: Fetch complete collection list (GET /api/v1/students)
router.get('/', (req, res) => {
  res.status(200).json({
    count: studentRecords.length,
    payload: studentRecords
  });
});

// Route B: Extract singular record dynamically via Route Parameters (GET /api/v1/students/:id)
router.get('/:id', (req, res) => {
  const targetRoll = req.params.id;
  const targetedStudent = studentRecords.find(s => s.rollNumber === targetRoll);
  
  if (!targetedStudent) {
    return res.status(404).json({
      status: "fail",
      error: `Student record matching roll index ${targetRoll} could not be located.`
    });
  }
  
  res.status(200).json({ status: "success", data: targetedStudent });
});

module.exports = router;


// 2. PRIMARY APPLICATION BOOTSTRAPPER FILE: index.js
// const express = require('express');
// const app = express();
// const studentRouter = require('./studentRouter');
// 
// app.use(express.json());
// 
// // Mounting the standalone router module onto a specific structural base endpoint URL
// app.use('/api/v1/students', studentRouter);
// 
// app.listen(5000);