Required query parameters in FastAPI - Mini Project: Build & Apply

Required Query Parameters in FastAPI

📖 Scenario: You are building a simple web API for a book store. You want to create an endpoint that requires users to provide the book_id as a query parameter to get details about a specific book.

🎯 Goal: Create a FastAPI endpoint that requires a book_id query parameter. The endpoint should return a JSON response with the book_id provided.

📋 What You'll Learn

Create a FastAPI app instance named app

Create a GET endpoint at path /book

Require a query parameter named book_id of type int

Return a dictionary with the key book_id and the value from the query parameter

💡 Why This Matters

🌍 Real World

APIs often require clients to send specific information as query parameters to fetch or filter data. This project shows how to enforce required query parameters in FastAPI.

💼 Career

Knowing how to handle required query parameters is essential for backend developers building RESTful APIs with FastAPI, a popular modern Python framework.

1

Create FastAPI app instance

Import FastAPI from fastapi and create an app instance called app.

FastAPI

from fastapi import FastAPI

# Create FastAPI app instance
# Your code here

Need a hint?

Use FastAPI() to create the app instance and assign it to app.

2

Define GET endpoint with required query parameter

Define a GET endpoint at path /book using @app.get("/book"). Add a function named get_book that takes a required query parameter book_id of type int.

FastAPI

from fastapi import FastAPI

app = FastAPI()

# Define GET endpoint at /book with required query parameter book_id
# Your code here

Need a hint?

Use function parameter typing to require book_id as an integer query parameter.

3

Return book_id in response

Inside the get_book function, return a dictionary with the key "book_id" and the value from the book_id parameter.

FastAPI

from fastapi import FastAPI

app = FastAPI()

@app.get("/book")
def get_book(book_id: int):
    # Return book_id in a dictionary
    # Your code here

Need a hint?

Return a dictionary with "book_id" as key and the function parameter book_id as value.

4

Add type hint and run the app

Ensure the book_id parameter is typed as int and the app is ready to run. (No extra code needed to run here, just confirm the final code structure.)

FastAPI

from fastapi import FastAPI

app = FastAPI()

@app.get("/book")
def get_book(book_id: int):
    return {"book_id": book_id}

# Finalize the code structure
# Your code here

Need a hint?

The code is complete and ready to run with uvicorn or similar server.