Glossary coding Term Page
pydantic-settings
Tool in the Pydantic v2 ecosystem that loads and validates external config into typed settings objects.
Core Idea
pydantic-settings extends Pydantic with a BaseSettings class that loads values from environment variables, .env files, or explicit keyword arguments and applies source precedence before validation. It enforces required secrets, supports custom validators, and understands helpers such as env_prefix and env_nested_delimiter.
Why It Matters Here
The FastAPI series relies on pydantic-settings to keep configuration declarative. By defining a single Settings object, Mathbong shows how to switch between local .env files and production secret stores without sprinkling os.environ lookups throughout the codebase.