Using JSF with Entity Relationships - EJB 3.0 Database Persistence with Oracle Fusion Middleware 11g - page 318

Section entity
Similarly, to the Section entity add named queries to find all Section entities and
find a Section entity by ID. As the Section entity has a one-to-many mapping with
the Article entity define a parameterized variable of type List for the Article entity.
Specify a @ManyToOne relationship with the Edition entity. If we want to initiate
merge, persist, refresh operations from the Section entity, we need to add a join
table on the Section entity side. But, if we don't want the associated Edition to
be deleted, then if the Section entity is deleted don't set the cascade element to
CascadeType.ALL . Set the fetch strategy to EAGER as we want to retrieve associated
entities when an entity is retrieved. The mappedBy element is not required to be set
in a unidirectional relationship; the mappedBy element is set on the non-owning side
of the relationship, which in the edition-section relationship is the Edition entity.
However, if you want to make the Section entity as the owning side too, add the
mappedBy element. The @ManyToOne relationship with the getter/setter methods for
the Edition entity is defined as follows:
@ManyToOne(cascade ={ CascadeType.MERGE, CascadeType.PERSIST,
CascadeType.REFRESH },fetch = FetchType.EAGER)
@JoinTable(name = "Edition_Section", joinColumns = {
@JoinColumn(name = "edition_id",
referencedColumnName = "id")} ,
inverseJoinColumns = {
@JoinColumn(name = "section_id",
referencedColumnName ="id")})
public Edition getEdition() {
return edition;
}
public void setEdition(Edition edition) {
this.edition = edition;
}
We also need to add a @OneToMany relationship to the Article entity. Set the
cascade element to CascadeType.ALL as we want to cascade all operations to the
Article entity. An Article entity without a Section entity wouldn't have much
significance. Set the mappedBy element to Section as the Section entity is the non-
owning side in the relationship. Add getter/setter methods for the Article entity
and also add add/remove methods to add and remove an Article entity:
@OneToMany(cascade = CascadeType.ALL, mappedBy = "section",
fetch = FetchType.EAGER)
@JoinTable(name = "Section_Article", joinColumns = {
@JoinColumn(name = "section_id",
referencedColumnName = "id")} ,
inverseJoinColumns = {