Admin vs user route protection in Express - Practice Questions

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when a non-admin user accesses an admin-only route?

Consider an Express app with middleware that checks if a user is an admin before allowing access to admin routes.

What will be the response if a logged-in user without admin rights tries to access /admin/dashboard?

Express

app.use('/admin', (req, res, next) => {
  if (!req.user || !req.user.isAdmin) {
    return res.status(403).send('Access denied');
  }
  next();
});

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

A The user receives a 403 status with 'Access denied' message.

B The user is redirected to the login page.

C The user sees 'Welcome to admin dashboard'.

D The server crashes with an error.

💡 Hint

Think about what the middleware does when the user is not an admin.

The middleware checks if req.user exists and if req.user.isAdmin is true. If not, it sends a 403 status with 'Access denied'. So non-admin users cannot reach the admin route handler.

📝 Syntax

intermediate

Which middleware correctly protects user routes but allows admins?

Choose the middleware that allows access to /user/profile only if the user is logged in, but admins can access all routes.

A app.use('/user', (req, res, next) => { if (!req.user && !req.user.isAdmin) return res.status(401).send('Login required'); next(); });

B app.use('/user', (req, res, next) => { if (!req.user) return res.redirect('/login'); next(); });

C app.use('/user', (req, res, next) => { if (!req.user || req.user.isAdmin) return res.status(401).send('Login required'); next(); });

D app.use('/user', (req, res, next) => { if (!req.user) return res.status(401).send('Login required'); next(); });

💡 Hint

Admins are also users, so check if the user is logged in regardless of admin status.

Option D checks if req.user exists, allowing both normal users and admins. Option D throws a TypeError when req.user doesn't exist (accessing .isAdmin). Option D blocks admins (condition true if req.user.isAdmin). Option D redirects instead of sending 401.

🔧 Debug

advanced

Why does the admin route allow all users despite the middleware?

Given this middleware, why does the /admin/settings route allow non-admin users?

Express

app.use('/admin', (req, res, next) => {
  if (!req.user.isAdmin) {
    res.status(403).send('Forbidden');
    return;
  }
  next();
});

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

A Because the middleware is not attached to the <code>/admin</code> route.

B Because <code>req.user.isAdmin</code> is always true by default.

C Because the middleware calls <code>next()</code> even after sending a response, allowing the route handler to run.

D Because the route handler overrides the middleware response.

💡 Hint

Think about what happens after res.status(403).send() is called.

After sending a response, the middleware still calls next(), so the request continues to the route handler, which sends a success response. The middleware should return after sending the response to stop further processing.

❓ state_output

advanced

What is the value of req.user in the admin middleware after login?

Assuming a login middleware sets req.user = { id: 1, isAdmin: true }, what will req.user be inside this admin middleware?

Express

app.use((req, res, next) => {
  req.user = { id: 1, isAdmin: true };
  next();
});

app.use('/admin', (req, res, next) => {
  // What is req.user here?
  next();
});

A { id: 1, isAdmin: true }

B undefined

C null

D {}

💡 Hint

Middleware runs in order. What does the first middleware do?

The first middleware sets req.user to the admin user object. The admin middleware runs after, so req.user is that object.

🧠 Conceptual

expert

Which approach best separates admin and user route protection in Express?

You want to protect admin routes and user routes separately in an Express app. Which design is best?

A Use a single middleware that checks if user is logged in and admin for all routes, then allow or deny accordingly.

B Use two separate middleware functions: one that checks if user is logged in for user routes, and another that checks if user is admin for admin routes.

C Check user role inside each route handler instead of middleware.

D Allow all users to access all routes and rely on frontend to hide admin features.

💡 Hint

Think about code clarity and security best practices.

Separating middleware for user and admin routes keeps code clear and secure. Option B mixes concerns and can be confusing. Option B scatters checks and is error-prone. Option B is insecure.