The best way to map a many-to-many association with extra columns when using JPA and Hibernate

Introduction For a simple many-to-many database relationship, you can use the @ManyToMany JPA annotation and, therefore, hide the join table. However, sometimes you need more than the two Foreign Key columns in the join table, and, for this purpose, you need to replace the @ManyToMany association with two bidirectional @OneToMany associations. Unlike unidirectional @OneToMany, the bidirectional relationship is the best way to map a one-to-many database relationship that requires a collection of Child elements on the parent side In this article, we are going to see how you can map a many-to-many… Read More

The best way to map a @OneToMany relationship with JPA and Hibernate

Introduction In a relational database system, a one-to-many association links two tables based on a Foreign Key column so that the child table record references the Primary Key of the parent table row. As straightforward as it might be in a RDBMS, when it comes to JPA, the one-to-many database association can be represented either through a @ManyToOne or a @OneToMany association since the OOP association can be either unidirectional or bidirectional. The @ManyToOne annotation allows you to map the Foreign Key column in the child entity mapping so that the child… Read More