Pydantic for JSON Validation in Python
In our last article(python simpleeval examples), we built a dynamic rules engine using simpleeval. But there is a golden rule in software engineering: Garbage In, Garbage Out.
If your rules engine expects a checkout cart to have a cart_total (a number) and a user_role (a string), but the frontend accidentally sends {"cart_total": "free", "role": null}, your engine will crash. Before untrusted JSON data ever reaches your core logic, it needs to pass through a strict gatekeeper. In modern Python, that gatekeeper is Pydantic.
