Middleware for authentication in Astro - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the middleware function correctly.

Astro

import [1] from 'astro/middleware';

Drag options to blanks, or click blank then click option'

AmiddlewareAuth

Bmiddleware

CauthMiddleware

DuseMiddleware

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect import names like authMiddleware or useMiddleware.

Forgetting to import middleware at all.

The middleware function is imported as middleware from 'astro/middleware'.

2fill in blank

medium

Complete the code to check if the user is authenticated inside the middleware.

Astro

export const onRequest = middleware(async ({ request, next }) => {
  if (!request.cookies.get('[1]')) {
    return new Response('Unauthorized', { status: 401 });
  }
  return next();
});

Drag options to blanks, or click blank then click option'

Aaccess_key

Bsession_id

Cuser_id

Dauth_token

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for unrelated cookie names like session_id or user_id.

Not checking cookies at all.

The middleware checks for the presence of the auth_token cookie to verify authentication.

3fill in blank

hard

Fix the error in the middleware function to correctly call the next handler.

Astro

export const onRequest = middleware(async ({ request, next }) => {
  if (!request.cookies.get('auth_token')) {
    return new Response('Unauthorized', { status: 401 });
  }
  return [1];
});

Drag options to blanks, or click blank then click option'

Aawait next

Bnext()

Cawait next()

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Returning the function reference without calling it.

Calling next without await in async function.

The next function is asynchronous and must be called with parentheses and awaited: await next().

4fill in blank

hard

Fill both blanks to create a middleware that redirects unauthenticated users to the login page.

Astro

export const onRequest = middleware(async ({ request, next }) => {
  if (!request.cookies.get([1])) {
    return new Response(null, {
      status: 302,
      headers: { Location: [2] }
    });
  }
  return await next();
});

Drag options to blanks, or click blank then click option'

A'auth_token'

B'session_id'

C'/login'

D'/home'

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong cookie names or redirect paths.

Not returning a proper redirect response.

The middleware checks for the 'auth_token' cookie and redirects to '/login' if missing.

5fill in blank

hard

Fill all three blanks to create middleware that logs the request method, checks authentication, and proceeds.

Astro

export const onRequest = middleware(async ({ request, next }) => {
  console.log('Request method:', [1]);
  if (!request.cookies.get([2])) {
    return new Response('Unauthorized', { status: 401 });
  }
  return await [3];
});

Drag options to blanks, or click blank then click option'

Arequest.method

B'auth_token'

Cnext()

Drequest.url

Attempts:

3 left

💡 Hint

Common Mistakes

Logging wrong request properties.

Checking wrong cookie names.

Not calling next() properly.

The middleware logs request.method, checks for 'auth_token' cookie, and calls next() to continue.

Practice

1. What is the main purpose of middleware for authentication in Astro?

easy

A. To fetch data from an external API after the page loads

B. To style the webpage with CSS before rendering

C. To check if a user is allowed to access certain pages before loading them

D. To optimize images automatically during build

Solution

1. Step 1: Understand middleware role

   Middleware runs before page loads to control access.

2. Step 2: Identify authentication purpose

   Authentication middleware checks user identity to allow or block access.

3. Final Answer:

   To check if a user is allowed to access certain pages before loading them -> Option C

4. Quick Check:

   Middleware controls access = A [OK]

Hint: Middleware controls access before page loads [OK]

Common Mistakes:

• Confusing middleware with styling or data fetching
• Thinking middleware runs after page loads
• Assuming middleware optimizes images

2. Which is the correct way to allow access to the next middleware or page in Astro authentication middleware?

easy

A. return context.stop()

B. return context.skip()

C. return context.block()

D. return context.next()

Solution

1. Step 1: Recall middleware flow control

   In Astro, calling context.next() passes control to next middleware or page.

2. Step 2: Identify correct method to continue

   Only context.next() allows access; others are invalid or block.

3. Final Answer:

   return context.next() -> Option D

4. Quick Check:

   Allow access = context.next() [OK]

Hint: Use context.next() to continue middleware chain [OK]

Common Mistakes:

• Using non-existent methods like context.stop()
• Confusing block and skip with next
• Omitting return keyword

3. Given this Astro middleware code snippet, what happens if the user is not authenticated?

export async function middleware(context) {
  if (!context.cookies.get('authToken')) {
    return new Response('Unauthorized', { status: 401 });
  }
  return context.next();
}

medium

A. The user sees a 401 Unauthorized response and page does not load

B. The user is redirected to the homepage

C. The middleware ignores the check and loads the page

D. The user is logged out automatically

Solution

1. Step 1: Analyze authentication check

   The code checks if 'authToken' cookie exists; if not, returns 401 response.

2. Step 2: Understand middleware response effect

   Returning a Response with status 401 stops page loading and shows unauthorized message.

3. Final Answer:

   The user sees a 401 Unauthorized response and page does not load -> Option A

4. Quick Check:

   Missing authToken = 401 response [OK]

Hint: Return Response with 401 to block unauthorized users [OK]

Common Mistakes:

• Assuming middleware redirects automatically
• Thinking page loads despite 401 response
• Confusing logout with blocking access

4. Identify the error in this Astro middleware code for authentication:

export async function middleware(context) {
  if (!context.cookies.get('authToken')) {
    context.next();
  }
  return new Response('Unauthorized', { status: 401 });
}

medium

A. The Response status 401 should be 200 to allow access

B. context.next() is called but its result is not returned, so middleware blocks all requests

C. The cookie name 'authToken' is incorrect and causes a runtime error

D. Middleware functions cannot be async in Astro

Solution

1. Step 1: Check middleware flow control

   context.next() must be returned to continue; here it is called but not returned.

2. Step 2: Understand effect of missing return

   Since return is after if-block, middleware always returns 401 response, blocking all requests.

3. Final Answer:

   context.next() is called but its result is not returned, so middleware blocks all requests -> Option B

4. Quick Check:

   Return context.next() to allow access [OK]

Hint: Always return context.next() to continue middleware chain [OK]

Common Mistakes:

• Calling context.next() without return
• Misunderstanding cookie name importance
• Thinking async is disallowed in middleware

5. You want to protect multiple private routes in Astro using middleware. Which approach correctly applies authentication middleware only to URLs starting with /dashboard or /settings?

hard

A. Check if context.url.pathname starts with '/dashboard' or '/settings' and run auth check only then

B. Apply middleware globally and always block access regardless of URL

C. Use middleware only on the homepage '/' to protect all routes

D. Check if context.url.pathname ends with '/dashboard' or '/settings' to run auth

Solution

1. Step 1: Understand route matching in middleware

   Middleware can check context.url.pathname to target specific routes.

2. Step 2: Identify correct string method for prefix matching

   Using startsWith matches routes beginning with '/dashboard' or '/settings'.

3. Step 3: Evaluate other options

   Blocking all routes or checking endsWith is incorrect for this purpose.

4. Final Answer:

   Check if context.url.pathname starts with '/dashboard' or '/settings' and run auth check only then -> Option A

5. Quick Check:

   Use startsWith for route prefix matching [OK]

Hint: Use startsWith to target route prefixes in middleware [OK]

Common Mistakes:

• Blocking all routes instead of specific ones
• Using endsWith instead of startsWith
• Applying middleware only on homepage