Repositories & Data Access

When to use this skill

• Create data access layer abstractions for entities
• Implement Bun-based repositories for database operations
• Define repository interfaces that services depend on
• Add transaction support (WithTx) to repositories

Key principles

1. Interface segregation: One repository interface per domain model
2. Bun ORM: Use Bun for type-safe database operations
3. Transaction support: Every repository implements WithTx(tx bun.IDB)
4. Context-aware: All operations accept context.Context
5. No business logic: Repositories only handle CRUD; logic lives in services

Pattern

Repositories are data access only:

• Define interface with CRUD operations (Create, GetByID, Update, Delete)
• Implement with Bun in bun_*.go files
• Accept bun.IDB at construction (not concrete *bun.DB)
• Return interfaces from constructors
• Missing records return nil, nil for single queries; empty slice for batch queries

Example

See examples/bun_todo_repository.go for:

• ITodoRepository interface definition
• bunTodoRepository Bun implementation
• CRUD and batch query patterns

Common mistakes

1. Returning errors for missing records (use nil instead)
2. Forgetting WithTx() method
3. Putting business logic in repositories
4. Not passing context to Scan/Exec
5. Repository-to-repository calls instead of service orchestration

References

• internal/repositories/interfaces.go - Core repository interfaces
• internal/repositories/bun_user_repository.go
• internal/repositories/bun_account_repository.go