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

Multiple query parameters

📖 Scenario: You are building a simple web API using FastAPI. Your API will accept multiple query parameters from the URL to filter a list of items.Imagine you have a store with products, and you want users to search products by category and price range using query parameters.

🎯 Goal: Create a FastAPI app that accepts two query parameters: category and max_price. The app should return a filtered list of products matching the category and with price less than or equal to max_price.

📋 What You'll Learn

Create a list of products as dictionaries with keys 'name', 'category', and 'price'.

Add query parameters category (string) and max_price (float) to the GET endpoint.

Filter the products list based on the query parameters.

Return the filtered list as JSON response.

💡 Why This Matters

🌍 Real World

APIs often need to accept multiple query parameters to filter or search data, like searching products by category and price.

💼 Career

Understanding how to handle multiple query parameters in FastAPI is essential for backend web development and building flexible APIs.

1

DATA SETUP: Create the products list

Create a list called products with these exact dictionaries: {'name': 'Apple', 'category': 'fruit', 'price': 1.2}, {'name': 'Banana', 'category': 'fruit', 'price': 0.5}, {'name': 'Carrot', 'category': 'vegetable', 'price': 0.8}, {'name': 'Steak', 'category': 'meat', 'price': 5.0}.

FastAPI

# Create the products list with exact items
# Your code here

Need a hint?

Use a list of dictionaries exactly as shown.

2

CONFIGURATION: Import FastAPI and create app

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

FastAPI

products = [
    {'name': 'Apple', 'category': 'fruit', 'price': 1.2},
    {'name': 'Banana', 'category': 'fruit', 'price': 0.5},
    {'name': 'Carrot', 'category': 'vegetable', 'price': 0.8},
    {'name': 'Steak', 'category': 'meat', 'price': 5.0}
]

# Import FastAPI and create app instance
# Your code here

Need a hint?

Use from fastapi import FastAPI and app = FastAPI().

3

CORE LOGIC: Create GET endpoint with query parameters

Create a GET endpoint at /items/ using @app.get("/items/"). Define a function read_items with two query parameters: category: str and max_price: float. Inside the function, filter products to include only items where item['category'] == category and item['price'] <= max_price. Return the filtered list.

FastAPI

from fastapi import FastAPI

app = FastAPI()

products = [
    {'name': 'Apple', 'category': 'fruit', 'price': 1.2},
    {'name': 'Banana', 'category': 'fruit', 'price': 0.5},
    {'name': 'Carrot', 'category': 'vegetable', 'price': 0.8},
    {'name': 'Steak', 'category': 'meat', 'price': 5.0}
]

# Create GET endpoint with query parameters category and max_price
# Your code here

Need a hint?

Use a list comprehension to filter products by category and max_price.

4

COMPLETION: Add type hints and async keyword

Ensure the endpoint function read_items is declared with async def and has type hints for category: str and max_price: float. Confirm the function returns the filtered list of products.

FastAPI

from fastapi import FastAPI

app = FastAPI()

products = [
    {'name': 'Apple', 'category': 'fruit', 'price': 1.2},
    {'name': 'Banana', 'category': 'fruit', 'price': 0.5},
    {'name': 'Carrot', 'category': 'vegetable', 'price': 0.8},
    {'name': 'Steak', 'category': 'meat', 'price': 5.0}
]

@app.get("/items/")
# Confirm async def and type hints
# Your code here

Need a hint?

Make sure the function is async and has correct type hints.