Rate limit error responses in Rest API - Mini Project: Build & Apply

Rate Limit Error Responses

📖 Scenario: You are building a simple REST API that limits how many requests a user can make in a short time. If the user sends too many requests, the API should respond with a clear error message and status code.

🎯 Goal: Create a basic API endpoint that tracks request counts per user and returns a rate limit error response when the limit is exceeded.

📋 What You'll Learn

Create a dictionary called request_counts to store user request counts.

Create a variable called MAX_REQUESTS and set it to 3.

Write a function called check_rate_limit(user_id) that increases the count for the user and returns True if under limit, False if limit exceeded.

Print the error response {"error": "Rate limit exceeded", "status": 429} when the limit is exceeded.

💡 Why This Matters

🌍 Real World

APIs often limit how many requests a user can make to protect servers and ensure fair use.

💼 Career

Understanding rate limiting is important for backend developers and API designers to build reliable and secure services.

1

Create the request count dictionary

Create a dictionary called request_counts that is empty initially.

Rest API

# Create an empty dictionary called request_counts
# Your code here

Need a hint?

Use curly braces {} to create an empty dictionary.

2

Set the maximum allowed requests

Create a variable called MAX_REQUESTS and set it to 3.

Rest API

request_counts = {}
# Create MAX_REQUESTS variable and set it to 3
# Your code here

Need a hint?

Just assign the number 3 to the variable MAX_REQUESTS.

3

Write the rate limit check function

Write a function called check_rate_limit(user_id) that does the following:
1. If user_id is not in request_counts, add it with value 1.
2. If user_id is already in request_counts, increase its count by 1.
3. Return True if the count is less than or equal to MAX_REQUESTS, otherwise return False.

Rest API

request_counts = {}
MAX_REQUESTS = 3
# Write check_rate_limit(user_id) function
# Your code here

Need a hint?

Use an if statement to check if the user is new, then update counts accordingly.

4

Print the rate limit error response

Call check_rate_limit("user1") five times in a loop. For each call, if it returns False, print the exact string {"error": "Rate limit exceeded", "status": 429}.

Rest API

request_counts = {}
MAX_REQUESTS = 3

def check_rate_limit(user_id):
    if user_id not in request_counts:
        request_counts[user_id] = 1
    else:
        request_counts[user_id] += 1
    return request_counts[user_id] <= MAX_REQUESTS

# Call check_rate_limit("user1") five times and print error if limit exceeded
# Your code here

Need a hint?

Use a for loop to call the function 5 times and print the error message only when the function returns False.