Module 2 — Path & Query Parameters

This module teaches you how to handle path parameters and query parameters in FastAPI. FastAPI automatically validates types and auto-documents your API.

1. Path Parameters

Path parameters are part of the URL structure.





from fastapi import FastAPI

app = FastAPI()

@app.get("/items/{item_id}")
async def get_item(item_id: int):
    return {"item_id": item_id}

2. Query Parameters

Query parameters come after the ? in the URL.





from fastapi import FastAPI
from typing import Optional

app = FastAPI()

@app.get("/search")
async def search_items(q: Optional[str] = None, limit: int = 10):
    return {"query": q, "limit": limit}

3. Combining Path + Query Parameters





from fastapi import FastAPI
from typing import Optional

app = FastAPI()

@app.get("/products/{product_id}")
async def read_product(product_id: int, q: Optional[str] = None, short: bool = False):
    return {
        "product_id": product_id,
        "query": q,
        "short_description": short
    }