Per-view caching in Django - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the decorator needed for per-view caching in Django.

Django

from django.views.decorators.cache import [1]

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

Acsrf_exempt

Blogin_required

Ccache_page

Drequire_http_methods

Attempts:

3 left

💡 Hint

Common Mistakes

Using decorators unrelated to caching like login_required.

Forgetting to import the decorator before using it.

The cache_page decorator is used to enable per-view caching in Django.

2fill in blank

medium

Complete the code to cache the view output for 15 minutes using the decorator.

Django

@cache_page([1])
def my_view(request):
    return HttpResponse('Hello World')

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

A900

B60

C3600

D300

Attempts:

3 left

💡 Hint

Common Mistakes

Using minutes directly instead of seconds.

Using too short or too long timeout values by mistake.

The argument to cache_page is the cache timeout in seconds. 15 minutes equals 900 seconds.

3fill in blank

hard

Fix the error in the decorator usage by completing the code correctly.

Django

@cache_page([1])
def product_list(request):
    # view code here
    pass

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

A15

B900

C'900'

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the timeout as a string instead of an integer.

Passing minutes instead of seconds.

The timeout must be an integer number of seconds, not a string or minutes.

4fill in blank

hard

Fill both blanks to import and apply the cache decorator to a view.

Django

from django.views.decorators.cache import [1]

@[2](60)
def homepage(request):
    return HttpResponse('Welcome!')

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

Acache_page

Blogin_required

Ccsrf_exempt

Drequire_http_methods

Attempts:

3 left

💡 Hint

Common Mistakes

Importing one decorator but using another.

Using decorators unrelated to caching.

You must import cache_page and use it as a decorator to cache the view.

5fill in blank

hard

Fill all three blanks to cache a view with a 5-minute timeout and import the decorator.

Django

from django.views.decorators.cache import [1]

@[2]([3])
def about(request):
    return HttpResponse('About us')

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

Acache_page

Blogin_required

C300

D900

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong timeout value.

Using a decorator unrelated to caching.

Import and use cache_page with a 300-second (5-minute) timeout.

Practice

1. What is the main purpose of using @cache_page(timeout) in Django views?

easy

A. To connect the view to the database

B. To save the view's output and speed up repeated visits

C. To validate user input before processing

D. To handle user authentication automatically

Solution

1. Step 1: Understand what caching does

   Caching stores the output of a view so it can be reused without recalculating.

2. Step 2: Recognize the role of @cache_page(timeout)

   This decorator saves the rendered page for the given timeout to speed up future requests.

3. Final Answer:

   To save the view's output and speed up repeated visits -> Option B

4. Quick Check:

   Per-view caching = save output for speed [OK]

Hint: Caching saves page output to speed up repeated visits [OK]

Common Mistakes:

• Thinking it validates input
• Confusing caching with authentication
• Assuming it connects to the database

2. Which of the following is the correct way to apply per-view caching with a 5-minute timeout in Django?

easy

A. @cache_page('300')
def my_view(request):
pass

B. @cache_page(5)
def my_view(request):
pass

C. @cache_page(timeout=5)
def my_view(request):
pass

D. @cache_page(300)
def my_view(request):
pass

Solution

1. Step 1: Understand the timeout parameter

   The timeout is in seconds, so 5 minutes = 300 seconds.

2. Step 2: Check correct syntax for @cache_page

   The decorator takes an integer timeout in seconds without quotes.

3. Final Answer:

   @cache_page(300)\ndef my_view(request):\n pass -> Option D

4. Quick Check:

   Timeout in seconds, no quotes = @cache_page(300) def my_view(request): pass [OK]

Hint: Timeout is seconds as integer, no quotes [OK]

Common Mistakes:

• Using string '300' instead of integer
• Passing timeout as minutes instead of seconds
• Using keyword argument timeout incorrectly

3. Given this Django view with per-view caching:

@cache_page(60)
def home(request):
    return HttpResponse(str(time.time()))

What will happen if you refresh the page multiple times within 60 seconds?

medium

A. The page shows the same timestamp for 60 seconds

B. The page shows a new timestamp on every refresh

C. The page raises an error because time.time() is not cached

D. The page shows timestamps increasing by 60 seconds

Solution

1. Step 1: Understand what @cache_page(60) does

   It caches the entire response for 60 seconds.

2. Step 2: Analyze the effect on time.time()

   Since the response is cached, the timestamp won't update until cache expires.

3. Final Answer:

   The page shows the same timestamp for 60 seconds -> Option A

4. Quick Check:

   Cache holds output unchanged for timeout [OK]

Hint: Cached view returns same output until timeout expires [OK]

Common Mistakes:

• Expecting timestamp to update every refresh
• Thinking caching only affects database queries
• Assuming cache raises errors with dynamic content

4. You wrote this Django view with caching:

from django.views.decorators.cache import cache_page

@cache_page('60')
def about(request):
    return HttpResponse('About page')

Why does this code cause an error?

medium

A. The timeout value is a string instead of an integer

B. The decorator is missing parentheses

C. The view function must be a class-based view

D. The import statement is incorrect

Solution

1. Step 1: Check the timeout argument type

   The timeout must be an integer number of seconds, not a string.

2. Step 2: Identify the error cause

   Passing '60' as a string causes a TypeError in the decorator.

3. Final Answer:

   The timeout value is a string instead of an integer -> Option A

4. Quick Check:

   Timeout must be int, not string [OK]

Hint: Timeout must be integer, not string [OK]

Common Mistakes:

• Using quotes around timeout number
• Forgetting parentheses on decorator
• Thinking function type matters here

5. You want to cache a Django view that shows user-specific data but still use per-view caching. Which approach correctly applies caching without showing wrong data to users?

hard

A. Cache the view globally and add user ID in the URL to separate cache keys

B. Use @cache_page(120) without changes; caching will separate users automatically

C. Use @cache_page(120) and add Vary: Cookie header to cache per user session

D. Do not use caching on user-specific views at all

Solution

1. Step 1: Understand caching user-specific data risks

   Global caching can show one user's data to others if not separated.

2. Step 2: Use Vary header to separate cache by user session

   Adding Vary: Cookie tells cache to store different versions per user session cookie.

3. Final Answer:

   Use @cache_page(120) and add Vary: Cookie header to cache per user session -> Option C

4. Quick Check:

   Vary header separates cache by user [OK]

Hint: Use Vary header to separate cache per user [OK]

Common Mistakes:

• Assuming caching separates users automatically
• Avoiding caching user views unnecessarily
• Adding user ID in URL without proper cache keys