Admin vs user route protection in Express - Hands-On Comparison

Admin vs User Route Protection in Express

📖 Scenario: You are building a simple web server using Express. The server has two types of users: admins and regular users. You want to protect certain routes so that only admins can access them, while other routes are open to all logged-in users.

🎯 Goal: Create an Express app that defines a user object with a role, sets up middleware to check if the user is an admin, and protects routes accordingly. The /admin route should only be accessible by admins, and the /dashboard route should be accessible by any logged-in user.

📋 What You'll Learn

Create a user object with a role property set to 'user' or 'admin'.

Create a middleware function called isAdmin that checks if the user role is 'admin'.

Protect the /admin route using the isAdmin middleware.

Create a /dashboard route accessible by any user.

💡 Why This Matters

🌍 Real World

Web apps often have different user roles. Protecting routes ensures only authorized users access sensitive pages.

💼 Career

Understanding route protection is key for backend developers to secure web applications and manage user permissions.

1

Create a user object with role

Create a constant called user with an object that has a role property set to the string 'user'.

Express

# Create a constant user object with role 'user'
# Your code here

Hint

Use const user = { role: 'user' }; to create the user object.

2

Create isAdmin middleware

Create a function called isAdmin that takes req, res, and next as parameters. Inside, check if user.role is equal to 'admin'. If yes, call next(). Otherwise, send a 403 status with the message 'Access denied'.

Express

const user = { role: 'user' };

// Create isAdmin middleware function
// Your code here

Hint

Check the user's role and call next() if admin, else send 403.

3

Protect /admin route with isAdmin middleware

Create an Express app by requiring express and calling it. Then create a /admin GET route that uses the isAdmin middleware. The route handler should send the text 'Welcome Admin'.

Express

const user = { role: 'user' };

function isAdmin(req, res, next) {
    if (user.role === 'admin') {
        next();
    } else {
        res.status(403).send('Access denied');
    }
}

// Require express and create app
// Create /admin route with isAdmin middleware
// Your code here

Hint

Use app.get('/admin', isAdmin, (req, res) => { res.send('Welcome Admin'); }).

4

Add /dashboard route accessible by any user

Add a GET route /dashboard to the Express app that sends the text 'User Dashboard'. This route should not use any middleware.

Express

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

const user = { role: 'user' };

function isAdmin(req, res, next) {
    if (user.role === 'admin') {
        next();
    } else {
        res.status(403).send('Access denied');
    }
}

app.get('/admin', isAdmin, (req, res) => {
    res.send('Welcome Admin');
});

// Add /dashboard route here
// Your code here

Hint

Use app.get('/dashboard', (req, res) => { res.send('User Dashboard'); }).

Practice

1. What is the main purpose of using middleware for admin vs user route protection in Express?

easy

A. To check user roles and allow or deny access accordingly

B. To speed up the server response time

C. To log every request made to the server

D. To change the URL of the route dynamically

Solution

1. Step 1: Understand middleware role

   Middleware runs before route handlers and can check conditions like user roles.

2. Step 2: Role-based access control

   Middleware can allow access only if the user has the right role, such as admin or user.

3. Final Answer:

   To check user roles and allow or deny access accordingly -> Option A

4. Quick Check:

   Middleware controls access = D [OK]

Hint: Middleware checks roles to protect routes [OK]

Common Mistakes:

• Thinking middleware speeds up server
• Confusing middleware with logging only
• Believing middleware changes URLs

2. Which of the following is the correct way to apply middleware for admin route protection in Express?

easy

A. app.get('/admin', (req, res) => adminMiddleware, res.send('Admin page'));

B. app.get('/admin', adminMiddleware, (req, res) => { res.send('Admin page'); });

C. app.use('/admin', (req, res) => { adminMiddleware(); res.send('Admin page'); });

D. app.get('/admin', (req, res) => { res.send('Admin page'); adminMiddleware(); });

Solution

1. Step 1: Understand middleware placement

   Middleware should be passed as a second argument before the route handler function.

2. Step 2: Check syntax correctness

   app.get('/admin', adminMiddleware, (req, res) => { res.send('Admin page'); }); correctly places adminMiddleware between route path and handler.

3. Final Answer:

   app.get('/admin', adminMiddleware, (req, res) => { res.send('Admin page'); }); -> Option B

4. Quick Check:

   Middleware before handler = A [OK]

Hint: Middleware goes between path and handler in route [OK]

Common Mistakes:

• Calling middleware inside handler instead of passing it
• Using middleware after sending response
• Passing middleware as a function call instead of reference

3. Given this middleware and route code, what will be the response if a user with role 'user' tries to access '/admin'?

function adminMiddleware(req, res, next) {
  if (req.user.role === 'admin') next();
  else res.status(403).send('Access denied');
}
app.get('/admin', adminMiddleware, (req, res) => {
  res.send('Welcome Admin');
});

medium

A. 'Access denied' with status 403

B. 'Welcome Admin'

C. Server error due to missing next()

D. Empty response with status 200

Solution

1. Step 1: Analyze middleware condition

   The middleware checks if req.user.role is 'admin'. If not, it sends 403 with 'Access denied'.

2. Step 2: User role is 'user'

   Since role is 'user', the else branch runs, sending 403 and 'Access denied'.

3. Final Answer:

   'Access denied' with status 403 -> Option A

4. Quick Check:

   Non-admin blocked with 403 = A [OK]

Hint: Check role condition in middleware to predict response [OK]

Common Mistakes:

• Assuming next() always runs
• Ignoring status code sent by middleware
• Thinking response is 'Welcome Admin' for all roles

4. Identify the error in this Express route protection code:

function adminMiddleware(req, res, next) {
  if (req.user.role === 'admin') next();
  else res.send('Access denied');
}
app.get('/admin', adminMiddleware, (req, res) => {
  res.send('Admin area');
});

medium

A. Route handler should be before middleware

B. Middleware should not call next()

C. Missing status code when sending 'Access denied'

D. req.user.role check is incorrect syntax

Solution

1. Step 1: Check middleware response

   When denying access, middleware sends a message but does not set HTTP status code.

2. Step 2: Importance of status code

   Without status 403, client gets status 200 which is misleading for access denial.

3. Final Answer:

   Missing status code when sending 'Access denied' -> Option C

4. Quick Check:

   Send 403 on denial = C [OK]

Hint: Always send status code with error messages [OK]

Common Mistakes:

• Not setting status code on error
• Calling next() after sending response
• Placing middleware after route handler

5. You want to protect two routes: '/admin' for admins only and '/profile' for logged-in users. Which Express setup correctly applies middleware for this scenario?

function authMiddleware(req, res, next) {
  if (req.user) next();
  else res.status(401).send('Login required');
}
function adminMiddleware(req, res, next) {
  if (req.user?.role === 'admin') next();
  else res.status(403).send('Admin only');
}
// Which setup is correct?

hard

A. app.get('/admin', adminMiddleware, authMiddleware, (req, res) => res.send('Admin')); app.get('/profile', adminMiddleware, (req, res) => res.send('Profile'));

B. app.get('/admin', (req, res) => res.send('Admin')); app.get('/profile', authMiddleware, (req, res) => res.send('Profile'));

C. app.get('/admin', authMiddleware, (req, res) => res.send('Admin')); app.get('/profile', adminMiddleware, (req, res) => res.send('Profile'));

D. app.get('/admin', authMiddleware, adminMiddleware, (req, res) => res.send('Admin')); app.get('/profile', authMiddleware, (req, res) => res.send('Profile'));

Solution

1. Step 1: Understand middleware order

   For '/admin', user must be logged in (authMiddleware) and have admin role (adminMiddleware).

2. Step 2: Apply correct middleware per route

   '/profile' only needs authMiddleware to check login. app.get('/admin', authMiddleware, adminMiddleware, (req, res) => res.send('Admin')); app.get('/profile', authMiddleware, (req, res) => res.send('Profile')); applies both correctly in order.

3. Final Answer:

   app.get('/admin', authMiddleware, adminMiddleware, (req, res) => res.send('Admin')); app.get('/profile', authMiddleware, (req, res) => res.send('Profile')); -> Option D

4. Quick Check:

   Auth then admin for admin route = B [OK]

Hint: Check middleware order: auth before admin [OK]

Common Mistakes:

• Reversing middleware order
• Using adminMiddleware alone for profile
• Not protecting admin route with authMiddleware