Pagination patterns in FastAPI - Mini Project: Build & Apply

Pagination patterns with FastAPI

📖 Scenario: You are building a simple API to serve a list of books. Since the list can be very long, you want to show only a few books per page. This is called pagination.Users will ask for a specific page number and get back only the books on that page.

🎯 Goal: Create a FastAPI app that returns a paginated list of books. The user can specify the page number and the number of books per page.

📋 What You'll Learn

Create a list of books as initial data

Add variables for page number and page size

Write the logic to select only the books for the requested page

Create a FastAPI endpoint that returns the paginated books

💡 Why This Matters

🌍 Real World

Pagination is used in APIs to avoid sending too much data at once. It helps users load data faster and reduces server load.

💼 Career

Understanding pagination is important for backend developers building APIs that serve large datasets efficiently.

1

Create the list of books

Create a list called books with these exact strings: 'Book A', 'Book B', 'Book C', 'Book D', 'Book E', 'Book F', 'Book G', 'Book H'.

FastAPI

# Create the list of books
# Your code here

Need a hint?

Use a Python list with the exact book names as strings.

2

Add pagination parameters

Create two variables: page set to 1 and page_size set to 3.

FastAPI

books = ['Book A', 'Book B', 'Book C', 'Book D', 'Book E', 'Book F', 'Book G', 'Book H']
# Create variables page and page_size
# Your code here

Need a hint?

Set page to 1 and page_size to 3 to show 3 books per page starting from page 1.

3

Select books for the current page

Create a variable start that calculates the first index for the current page using page and page_size. Then create end as start + page_size. Finally, create paginated_books as the slice of books from start to end.

FastAPI

books = ['Book A', 'Book B', 'Book C', 'Book D', 'Book E', 'Book F', 'Book G', 'Book H']
page = 1
page_size = 3
# Calculate start and end indexes and slice books
# Your code here

Need a hint?

Remember that list slicing in Python uses list[start:end] and that page 1 starts at index 0.

4

Create FastAPI endpoint for pagination

Import FastAPI and create an app instance called app. Then create a GET endpoint /books/ that accepts query parameters page and page_size with default values 1 and 3. Inside the endpoint function, calculate start and end as before, slice books to get paginated_books, and return it as JSON.

FastAPI

books = ['Book A', 'Book B', 'Book C', 'Book D', 'Book E', 'Book F', 'Book G', 'Book H']
page = 1
page_size = 3
start = (page - 1) * page_size
end = start + page_size
paginated_books = books[start:end]

# Import FastAPI and create app
# Create GET endpoint /books/ with page and page_size query parameters
# Calculate start, end, and return paginated_books
# Your code here

Need a hint?

Use query parameters with default values in the endpoint function. Return the sliced list as JSON.