Hands-on Practice 1

Step-by-Step Coding Procedure:

1. Setup and Initialize Project:

   • Create a project folder express-crud-app.

   • Initialize Node project and install Express:

     mkdir express-crud-app && cd express-crud-app
     npm init -y
     npm install express

2. Create Basic Server (index.js):

   • Set up basic Express server index.js for Managing User

// Create index.js:

const express = require('express');
const app = express();
const PORT = 3000;

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

// Sample user data
let users = [
  { id: 1, name: 'Alice', email: '[e-mail]' },
  { id: 2, name: 'Bob', email: '[e-mail]' },
];

// GET all users
app.get('/users', (req, res) => {
  res.json(users);
});

// GET a specific user by ID
app.get('/users/:id', (req, res) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  if (user) {
    res.json(user);
  } else {
    res.status(404).send('User not found');
  }
});

// POST a new user
app.post('/users', (req, res) => {
  const newUser = { id: users.length + 1, ...req.body };
  users.push(newUser);
  res.status(201).json(newUser);
});

// PUT to update a user
app.put('/users/:id', (req, res) => {
  const index = users.findIndex(u => u.id === parseInt(req.params.id));
  if (index !== -1) {
    users[index] = { id: parseInt(req.params.id), ...req.body };
    res.json(users[index]);
  } else {
    res.status(404).send('User not found');
  }
});

// DELETE a user
app.delete('/users/:id', (req, res) => {
  users = users.filter(u => u.id !== parseInt(req.params.id));
  res.status(204).send();
});

// Start the server
app.listen(PORT, () => {
  console.log(`Server running on http://localhost:${PORT}`);
});

1. Implement CRUD Operations:

• Create RESTful API routes for managing users as shown above.

• RESTful API Routes for Managing Users:

// index.js
const express = require('express');
const app = express();
const PORT = 3000;

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

let users = [
  { id: 1, name: 'Alice', email: '[e-mail]' },
  { id: 2, name: 'Bob', email: '[e-mail]' }
];

// GET all users
app.get('/users', (req, res) => {
  res.json(users);
});

// GET a specific user by ID
app.get('/users/:id', (req, res) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  if (user) {
    res.json(user);
  } else {
    res.status(404).send('User not found');
  }
});

// POST a new user
app.post('/users', (req, res) => {
  const newUser = { id: users.length + 1, ...req.body };
  users.push(newUser);
  res.status(201).json(newUser);
});

// PUT to update a user
app.put('/users/:id', (req, res) => {
  const index = users.findIndex(u => u.id === parseInt(req.params.id));
  if (index !== -1) {
    users[index] = { id: parseInt(req.params.id), ...req.body };
    res.json(users[index]);
  } else {
    res.status(404).send('User not found');
  }
});

// DELETE a user
app.delete('/users/:id', (req, res) => {
  users = users.filter(u => u.id !== parseInt(req.params.id));
  res.status(204).send();
});

app.listen(PORT, () => {
  console.log(`Server running on http://localhost:${PORT}`);
});

Testing with Postman:

4. Testing with Postman:

• GET: Retrieve All Users

  • Open Postman.

  • Select GET from the dropdown.

  • Enter http://localhost:3000/users in the URL field.

  • Click Send.

  • Expected Result: A list of all users in JSON format.

  POST: Add a New User

  • Select POST from the dropdown.

  • Enter http://localhost:3000/users in the URL field.

  • Go to the Body tab, select raw, and choose JSON format from the dropdown.

  • Enter the following JSON data:

    {
      "name": "Charlie",
      "email": "[e-mail]"
    }

  • Click Send.

  • Expected Result: The new user object is returned with an assigned ID.

  PUT: Update User Details

  • Select PUT from the dropdown.

  • Enter http://localhost:3000/users/1 (replace 1 with the user ID you want to update).

  • Go to the Body tab, select raw, and choose JSON format.

  • Enter the updated JSON data:

    {
      "name": "Alice Updated",
      "email": "[e-mail]"
    }

  • Click Send.

  • Expected Result: The updated user object is returned.

  DELETE: Remove a User

  • Select DELETE from the dropdown.

  • Enter http://localhost:3000/users/1 (replace 1 with the user ID you want to delete).

  • Click Send.

  • Expected Result: No content returned (status code 204), indicating the user was successfully deleted.

  By following these steps, you'll be able to effectively test your RESTful API endpoints using Postman.

Student Activity:

• Build a RESTful API to manage a "tasks" list (similar CRUD operations as above).

• Test all API endpoints using Postman.

• Bonus: Add validation to ensure all fields are correctly provided before adding or updating a user.

By the end of this session, students will understand key Node.js and Express concepts, be able to build web applications, and create RESTful APIs with real-world examples.