Question

Firstly, I am somewhat new with Hibernate. To get to know the technology I am using it in a project. I am trying to map the following database:

Campaign
  campaignId(+)
  name

Promotion
  campaignId(+)
  discount(+)
  product
  message

I’ve indicated the primary key in both cases with a (+). The ‘campaignId’ in Promotion is a foreign key to Campaign to model the 1:m mapping (A Campaign has many Promotions). Using annotations I am stuck on how to do this.

I do not really want to add a promotionId in the Promotion table as it makes working with the data cumbersome. This of course, makes the bridging table a bit tricky. I also have problems working with a foreign key that is also part of the primary key.

Is a mapping for this possible at all?

---

Ok, I got it working. Sort of. Have to check if persistence actually work. I did the following:

@Entity
@Table(name = "CAMPAIGNS")
@Audited
public class CampaignEntity {
    private int campaignId;
    private String name;
    private List<PromotionEntity> promotions;

    public CampaignEntity(int campaignId, String name) {
        this.campaignId = campaignId;
        this.name = name;
    }

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "cmp_id")
    public int getCampaignId() {
        return campaignId;
    }

    public void setCampaignId(int campaignId) {
        this.campaignId = campaignId;
    }

    // Campaign name here... left out to save space

    @OneToMany
    @JoinColumn(name = "cmp_id")
    public List<PromotionEntity> getPromotions() {
        return promotions;
    }

    public void setPromotions(List<PromotionEntity> promotions) {
        this.promotions = promotions;
    }
}

Promotion is a vanilla mapping (not using embedded after all), with the fields: campaignId, discount, message. (It also does not have a @ManyToOne annotation.)

Does that make sense?

Lastly, and this will be first prize: as you can see I’m using Envers to audit the whole thing. The above creates a rather ugly “CampaignEntity_PromotionEntity_AUD” table. I understand that it is needed, but how can I rename it to CAMPAIGN_PROMOTION_AUD rather?

Thanks guys!

---

I got an answer on a lonely website deeply hidden away in far-corners of the Hibernate’s Jira error tracking website: https://hibernate.onjira.com/browse/HHH-3729.

The answer is to use @AuditJoinTable(name = “CAMPAIGN_PROMOTION_AUD”) of course.

Answer 1

This is what I am now using. It works well and Hibernate handles the PKs of the Promotions for me. Thanks again.

@Entity
@Table(name = "CAMPAIGNS")
@Audited
public class CampaignEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false)
    private Integer campaignId;

    @Column(name = "name", nullable = false, unique = true)
    private String campaignName;

     @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
     @JoinTable(name = "CAMPAIGN_PROMOTIONS", 
                joinColumns = { @JoinColumn(name = "campaign_id") }, 
                inverseJoinColumns = { @JoinColumn(name = "promotion_id") })
     private Set<PromotionEntity> promotions;

     ...
}

and then, PromotionEntity:

@Entity
@Table(name = "PROMOTIONS")
@Audited
public class PromotionEntity implements Comparable<PromotionEntity> {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @Column(name = "discount", nullable = false)
    private Integer discount;

    @Column(name = "message", nullable = false)
    private String message;

    ...
}

I also prefer annotating the fields rather than the getters as it is more compact and reads easier.