One-To-Many Relationship in Spring Data JPA

Question

I would like to have a One-to-many relationship between 2 Entities, Consumer and Policy. One consumer should have several policies.

This is an example of a Consumer

Answer 1

@Entity
public class Consumer {

    @OneToMany(mappedBy = "consumer")
    private List policies;

}

@Entity
public class Policy {

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn("consumer_id")
    private Consumer consumer;

}

fetch = FetchType.LAZY is not necessary, but desirable.

I have provided some basics here

what is @JoinColumn and how it is used in Hibernate

If you want to a Policy don't have a Consumer:

You can use a join table

@Entity
public class Consumer {

    @OneToMany
    private List policies;

}

@Entity
public class Policy {

}

A unidirectional relation (a Policy table will have consumer_id column, but a Policy class doesn't have a Consumer)

@Entity
public class Consumer {

    @OneToMany
    @JoinColumn("consumer_id")
    private List policies;

}

@Entity
public class Policy {

}

Also, keep in mind, that if you want to use a Policy as a reference (from a dictionary) you will need @ManyToMany.