> For the complete documentation index, see [llms.txt](https://reactjs.koida.tech/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://reactjs.koida.tech/backend-frameworks-next.js/hands-on-practice-1.md).

# 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**

```javascript
// 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: 'alice@example.com' },
  { id: 2, name: 'Bob', email: 'bob@example.com' },
];

// 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}`);
});

```

3. **Implement CRUD Operations:**

* Create RESTful API routes for managing `users` as shown above.
* **RESTful API Routes for Managing Users:**

```javascript
// 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: 'alice@example.com' },
  { id: 2, name: 'Bob', email: 'bob@example.com' }
];

// 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:

    ```json
    {
      "name": "Charlie",
      "email": "charlie@example.com"
    }
    ```
  * 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": "alice.updated@example.com"
    }
    ```
  * 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.


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