Throttling for rate limiting in Django - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is throttling in Django REST Framework?

Throttling is a way to limit the number of requests a user can make to an API in a given time. It helps protect the server from too many requests and keeps the service stable.

beginner

Name two built-in throttling classes in Django REST Framework.

Two common throttling classes are AnonRateThrottle for anonymous users and UserRateThrottle for authenticated users.

intermediate

How do you set a rate limit for throttling in Django REST Framework?

You set rate limits in the REST_FRAMEWORK settings using the DEFAULT_THROTTLE_RATES dictionary. For example, {'user': '100/day'} means 100 requests per day per user.

beginner

What happens when a user exceeds the throttle limit in Django REST Framework?

The API returns a 429 Too Many Requests response. This tells the user to slow down and try again later.

intermediate

How can you apply throttling only to specific views in Django REST Framework?

You can add the throttle_classes attribute to a view or viewset and list the throttling classes you want to apply. This way, throttling is not global but limited to those views.

Which Django REST Framework setting controls the rate limits for throttling?

A DEFAULT_THROTTLE_RATES

B THROTTLE_CLASSES

C RATE_LIMIT_SETTINGS

D API_THROTTLE_LIMITS

The DEFAULT_THROTTLE_RATES setting defines the allowed request rates for different throttle classes.

What HTTP status code does Django REST Framework return when a user is throttled?

A 403 Forbidden

B 400 Bad Request

C 401 Unauthorized

D 429 Too Many Requests

When throttling limits are exceeded, the API returns a 429 Too Many Requests status.

Which throttling class is used for anonymous users by default?

A ScopedRateThrottle

B UserRateThrottle

C AnonRateThrottle

D BaseThrottle

AnonRateThrottle limits requests from users who are not logged in.

How can you apply different throttling rates to different API views?

A Set <code>throttle_classes</code> on each view

B Change <code>DEFAULT_THROTTLE_RATES</code> globally

C Use middleware to filter requests

D Modify the database throttle table

You can specify throttle_classes on views to apply throttling selectively.

What is the main purpose of throttling in APIs?

A To speed up responses

B To limit request rates and protect the server

C To authenticate users

D To cache API responses

Throttling limits how often users can call the API to prevent overload.

Explain how throttling works in Django REST Framework and why it is important.

Think about how you would stop someone from calling your API too many times too fast.

Describe how to configure throttling rates and apply throttling to specific views in Django REST Framework.

Consider both the settings file and the view code.

Practice

1. What is the main purpose of throttling in Django REST Framework?

easy

A. To cache API responses for faster access

B. To limit the number of requests a user can make in a given time period

C. To authenticate users before accessing the API

D. To speed up the response time of the server

Solution

1. Step 1: Understand throttling concept

   Throttling is designed to control how many requests a user can send to the server in a set time.

2. Step 2: Identify purpose in Django REST Framework

   It prevents abuse by limiting request rates, not speeding responses or authentication.

3. Final Answer:

   To limit the number of requests a user can make in a given time period -> Option B

4. Quick Check:

   Throttling = request limit [OK]

Hint: Throttling controls request counts per time [OK]

Common Mistakes:

• Confusing throttling with authentication
• Thinking throttling speeds up responses
• Mixing throttling with caching

2. Which of the following is the correct way to set a throttle rate of 10 requests per minute in a custom throttle class?

easy

A. rate = '10/minute'

B. rate = '10/second'

C. rate = 'minute/10'

D. rate = '10 requests per minute'

Solution

1. Step 1: Recall throttle rate format

   The rate must be a string with number and time unit separated by a slash, e.g., '10/minute'.

2. Step 2: Match correct syntax

   Only '10/minute' matches the required format; others are invalid or incorrect syntax.

3. Final Answer:

   rate = '10/minute' -> Option A

4. Quick Check:

   Throttle rate format = 'number/time' [OK]

Hint: Throttle rate uses 'number/time' string format [OK]

Common Mistakes:

• Using spaces or words instead of slash format
• Swapping number and time units
• Using unsupported time units

3. Given this view with throttling applied:

from rest_framework.throttling import UserRateThrottle

class MyThrottle(UserRateThrottle):
    rate = '3/minute'

class MyView(APIView):
    throttle_classes = [MyThrottle]

    def get(self, request):
        return Response({'message': 'Hello'})

What happens if a user makes 4 GET requests within one minute?

medium

A. The 4th request is delayed but eventually succeeds

B. All 4 requests succeed with status 200

C. The 4th request is blocked with a 429 Too Many Requests error

D. The server crashes due to too many requests

Solution

1. Step 1: Understand throttle rate and behavior

   The throttle allows 3 requests per minute per user; the 4th exceeds the limit.

2. Step 2: Identify response to exceeding limit

   When limit is exceeded, Django REST Framework returns HTTP 429 error blocking the request.

3. Final Answer:

   The 4th request is blocked with a 429 Too Many Requests error -> Option C

4. Quick Check:

   Requests > rate limit = 429 error [OK]

Hint: Requests over limit get 429 error [OK]

Common Mistakes:

• Assuming all requests succeed
• Thinking requests get delayed instead of blocked
• Believing server crashes on too many requests

4. Identify the error in this custom throttle class:

from rest_framework.throttling import SimpleRateThrottle

class CustomThrottle(SimpleRateThrottle):
    scope = 'custom'

    def get_cache_key(self, request, view):
        return request.user.id

# settings.py
REST_FRAMEWORK = {
    'DEFAULT_THROTTLE_RATES': {
        'custom': '5/minute'
    }
}

medium

A. get_cache_key should return a string, but returns an integer

B. scope should be set to 'rate' instead of 'custom'

C. DEFAULT_THROTTLE_RATES key 'custom' is missing a time unit

D. CustomThrottle must inherit from UserRateThrottle, not SimpleRateThrottle

Solution

1. Step 1: Check get_cache_key return type

   The method returns request.user.id, which is an integer, but cache keys must be strings.

2. Step 2: Validate other parts

   Scope 'custom' matches the throttle rate key, and inheritance from SimpleRateThrottle is valid.

3. Final Answer:

   get_cache_key should return a string, but returns an integer -> Option A

4. Quick Check:

   Cache key must be string [OK]

Hint: Cache keys must be strings, not integers [OK]

Common Mistakes:

• Returning non-string cache keys
• Misnaming throttle scope
• Confusing throttle class inheritance

5. You want to apply different throttle rates for authenticated and anonymous users in Django REST Framework. Which approach correctly implements this?

hard

A. Set a single throttle class with rate '10/minute' and check user status inside get_cache_key

B. Use middleware to block anonymous users after 5 requests per minute instead of throttling classes

C. Apply throttling only to authenticated users by setting throttle_classes conditionally in the view

D. Use two throttle classes: one with 'user' scope for authenticated, one with 'anon' scope for anonymous, and add both to the view's throttle_classes

Solution

1. Step 1: Understand throttling for different user types

   Django REST Framework supports multiple throttle classes to handle different user types separately.

2. Step 2: Apply correct method

   Using two throttle classes with 'user' and 'anon' scopes and adding both to throttle_classes is the standard way.

3. Final Answer:

   Use two throttle classes: one with 'user' scope for authenticated, one with 'anon' scope for anonymous, and add both to the view's throttle_classes -> Option D

4. Quick Check:

   Multiple throttle classes handle user types separately [OK]

Hint: Use separate throttle classes for user and anon [OK]

Common Mistakes:

• Trying to handle both user types in one throttle class
• Using middleware instead of throttle classes
• Conditionally setting throttle_classes in the view