JPA and Hibernate provide 3 main options to map a Collection. If it’s a Collection of other entities, you can model it as a to-many association. This is the most common mapping. But you can also map it as an @ElementCollection or as a basic type. In this article, I will show you all 3…
When you model a hierarchical data structure, you often have to use self-referencing associations. Both ends of these associations are of the same type. In other words, the entity object on which the association is defined and the one the association references are of the same type. In your database, you model that using a…
An association between 3 entities is called a ternary association. A typical example is an association between an employee, the project they are working on, and their role in that project. If the role is a complex object, you might decide to model this as 3 entity classes. The association between them is the interesting…
The java.util.List<SomeEntityClass> is the most common representation of a to-many association with JPA and Hibernate. But is it also the one that you want to use in your domain model? Does it fit your use cases or do you need smarter access to the associated elements? Let’s be honest, a simple java.util.List is good enough…
