Pydantic

This is a comprehensive reference for Pydantic V2 that covers the validation patterns you actually need when building customer support systems or any data-heavy backend. It walks through BaseModel basics, Field constraints with real validation rules, custom validators for business logic like checking email domains or filtering spam, and model-level validation for cross-field checks. The examples are concrete: support tickets, customer profiles, attachment validation with file extension checks. It's aimed at teams who need to sanitize user input, validate API requests, or manage configuration with type safety. The code samples are production-ready and show proper error handling, which matters when you're dealing with support data at scale.