38. Validating and Sanitizing Network Data

Never trust data from external APIs. Validate format and content before using.

Example

import requests

response = requests.get("https://api.exchangerate.host/latest", timeout=5)
data = response.json()
if "rates" not in data or not isinstance(data["rates"], dict):
    raise ValueError("Invalid API response structure.")
print("Base currency:", data.get("base"))

✅ Lesson: Treat API responses as untrusted input — validate structure and content before use.