DDD Python

Tactical Domain-Driven Design patterns for Python projects. Uses dataclasses or Pydantic for value objects and entities, ABCs for ports, and SQLAlchemy for the repository implementation.

When to Activate

• Structuring a Python service with complex business rules
• Implementing entities, value objects, or aggregates in Python
• Defining repository interfaces and SQLAlchemy implementations
• Adding domain events and application service layers
• Refactoring Django/FastAPI code towards hexagonal architecture
• Deciding how to model a domain concept as an entity vs. a value object in Python
• Wiring DDD patterns into a FastAPI or Django project without leaking domain logic into views

Entities

Entities have identity (an id field) that persists over time. Equality is by identity, not value.