dabydat/alpha-omega/nestjs-repository-pattern

NestJS Repository Pattern

Repository is the collection-like interface for accessing aggregates. It abstracts data persistence, keeping domain independent of database implementation.

Production patterns for: Data access, repository interfaces, TypeORM implementations, DI configuration

Agent collaboration: Backend Dev (repository pattern, no raw queries), DBA (index design, query optimization)

Core Principle: Repository is a Collection

See references/why-repository.md for the collection metaphor, the ❌ BAD SQL-in-domain example, and the ✅ GOOD interface example.

Repository Interface (Domain Layer)

See references/repository-interface.md for the ENTITY_REPOSITORY symbol, the interface, and common methods.

TypeORM Implementation (Infrastructure)

See references/typeorm-implementation.md for the EntityRepositoryImpl.

Paginated Queries

See references/paginated-queries.md for findPaginated (findAndCount).

Transaction Support

See references/transaction.md for transaction via manager and usage in a command handler.

Complex Queries (Query Builder)

See references/query-builder.md for findByCriteria.

Module Registration

See references/module-registration.md for binding interface→implementation.

Anti-Patterns to Avoid

See references/anti-patterns.md for the four ❌ examples (persistence return, business logic, no pagination, raw query in service).

Summary: Repository Responsibilities

Golden rule: Repository is the gate to persistence. Domain never talks directly to database. Only through repository.