Best practices to write an Entity in Spring/Hibernate

• Every entity has to have a public default contstructor
• fetchType = FetchType.LAZY on @OneToOne, @OneToMany and @ManyToOne and other associations (EAGER is the default except @OneToMany)
• If an association is not mandatory:
  • optional = false on association annotations
  • @Column and @JoinColumn should contain nullable = false
• Entity should implement Persistable<IDTYPE> interface
  • Create own interface with default implementation:

 public interface Identifiable extends Persistable<Long> { 
     default isNew() { 
         return getId() == null; 
     }
 }

• All ids should be boxed like Long, Integer, String, etc. (Implementing Persistable<IDTYPE> will ensure this.)
• Do not use lombok for entities (hibernate), generated code interfere with each other
• Do not reimplement equals and hashCode for entities
• Do not use primitives if they can be null in the DB

In the service layer:

• Use @Transactional(readOnly = true) if the method can write db or @Transactional(readOnly = false) if not (false is the default in spring)