Spring Boot Patterns

Files: skills/springboot-patterns/SKILL.md + skills/jpa-patterns/SKILL.md

JPA/Hibernate Patterns

Entity Design

• @EntityListeners(AuditingEntityListener.class) for @CreatedDate/@LastModifiedDate
• @Enumerated(EnumType.STRING) for enum fields
• Indexes on common query fields

N+1 Prevention

• Default to lazy loading
• JOIN FETCH in JPQL when eager loading needed
• DTO projections for read-only paths

Repository

• Spring Data JPA interfaces with custom JPQL
• Interface-based projections for lightweight queries
• Cursor pagination: id > :lastId with ordering

Transactions

@Transactional on service methods. readOnly = true for queries. Short transactions.

Connection Pool (HikariCP)

maximum-pool-size=20, minimum-idle=5, connection-timeout=30000

Migrations

Flyway or Liquibase. Never Hibernate auto DDL in production.

Testing

@DataJpaTest with Testcontainers. Verify SQL efficiency via Hibernate SQL logging.

Production Defaults

• Constructor injection (no field injection)
• spring.mvc.problemdetails.enabled=true (RFC 7807)
• Null-safety via @NonNull and Optional
• Structured JSON logging via Logback
• Metrics: Micrometer + Prometheus/OTel

Remember: Keep controllers thin, services focused, repositories simple, errors handled centrally.