gobetterauth/services-and-interfaces

Services & Interface Design

When to use this skill

• Create services that encapsulate business logic
• Implement business operations that delegate to repositories
• Add authentication or domain-specific features as services

Key principles

1. Concrete struct design: Services are concrete structs
2. Constructor-based injection: Dependencies passed at construction
3. Single responsibility: Each service handles one domain concern
4. Repository delegation: Services delegate all data access to repositories
5. Context-aware: All public methods accept context.Context

Pattern

Services handle business logic:

• Define interface (optional but recommended)
• Implement as concrete struct with repository dependencies
• Constructor function injects all dependencies
• Methods are thin wrappers that validate, transform, and delegate to repositories
• Return interfaces from constructors

Example

See examples/todo_service.go for:

• TodoService interface definition
• todoService implementation
• Validation and repository delegation patterns

Common mistakes

1. Service-to-service direct calls without interfaces
2. Putting queries in services (repositories own data access)
3. Missing context parameter
4. Exporting implementation struct instead of interface
5. Not testing with mocks

References

• services/core.go - Core service interfaces
• internal/services/user_service.go
• internal/services/account_service.go