best-practices.md

title	Best Practices
description	Architecture, database, security, and testing best practices for IDP-Core

🏗️ Architecture

• Dependency Rule: Domain depends on nothing.
• Interface Segregation: Keep interfaces focused, for example EntityTemplateRepository vs generic Repository.
• Exceptions: Throw business exceptions in Domain, handle them in Infrastructure.

💾 Database

• Migrations: Always use Flyway. Never modify existing migration files, they are cumulative and immutable.
• JPA: Use FetchType.LAZY by default. Use JOIN FETCH for performance only where necessary.

🔒 Security

• Validation: Validate at DTO level (@Valid) and Database level (unique=true).

🧪 Testing

• Data: Use dedicated JSON files for test data.
• Builders: Use Builder pattern for creating test objects.