Hibernate and Spring - Unleash the Magic
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This document provides an overview of several Java technologies: - JPA Auditing for tracking entity creation/modification dates and users - Domain Events in DDD for triggering processing across aggregates - javax.validation for validating entities before database writes - Spring Data Repos for implementing repositories with query methods and custom logic It also briefly discusses JPA auditing implementation, domain event publishing, custom validators, and the @NonNullApi annotation for preventing null returns from repositories.
Hibernate and Spring - Unleash the Magic
- 2. Victor Rentea VictorRentea.ro Recorded Talks, Blog, Video Courses, ... Independent Trainer Founder of Bucharest Software Craftsmanship Community Java Champion ❤️ Simple Design, Refactoring, Unit Testing ❤️
- 3. Training 500 days (200+ online) 2000 devs 8 years 50+ companies Reach out to me: Hibernate Spring Func Prog Java Performance Reactive Prog Design Patterns Pragmatic DDD Clean Code Refactoring Unit Testing TDD @victorrentea Intense Video Courses: victorrentea.teachable.com More: VictorRentea.ro
- 4. VictorRentea.ro 74 ¡¡ PLEASE !! Ask questions!
- 6. Get Set .... • JPA Auditing • Domain Events • javax.validation • Spring Data Repos
- 7. JPA Auditing • @CreatedBy / Date • @LastModifiedBy / Date • Relies on @PrePersist, @PreUpdate JPA Hooks defined via • @EntityListeners on @Entity or • global via orm.xml • User is retrieved from an AuditorAware • Typically from Spring Security Session (SecurityContextHolder)
- 8. Domain Events (DDD) • Problem: logic inside an @Entity methods needs to trigger further processing, involving other unrelated Aggregates • At .save(e), the Entity is scanned for a @DomainEvents getter • Pitfall: What if I forget to .save()? • Pitfall: Auto-flushing the dirty entity does NOT publish the events ➔Alternative: static EventPublisherHolder • Events are delivered to all interested @EventListener • In the same transaction (default, safest) • After the current transaction COMMITS - @TransactionalEventListener
- 9. javax.validation • Before writing to DB, @Entities are automatically validated: • @NotNull • @Size(min=) • @Pattern(regexp=) • ... • Custom Validators (even loaded from Spring)
- 10. CustomerRepository Customer findByName(String name); @Query("SELECT c FROM Cust... ") List<Customer> getActiveCustomers(); JpaRepository<E,ID> List<E> findAll(); E findOne(ID); void save(E); void delete(E); ... CustomerRepositoryCustom List<Customer> search(CustomerSearch); CustomerRepositoryImpl List<Customer> search(CustomerSearch) { ...<implem>... } CustomBaseRepository<E,ID> E findExactlyOne(ID id); CustomBase RepositoryImpl <implem> naming convention Spring Data Repo Architecture JpaSpecificationExecutor<E> List<E> findAll(Specification<E> spec); QuerydslPredicateExecutor<E> List<E> findAll(Predicate spec); Codegeneration via Maven Plugin
- 11. @NonNullApi on ...repo/package-info.java Repo method cannot return null anymore You have to return Optional<>
- 12. Finish! • JPA Auditing • Domain Events • javax.validation • Spring Data Repos
- 13. If you decide to use magic make sure THE ENTIRE team understands it