JPA Mapping @EmbeddedId with ManyToOne relationship

Question

so I searched for the answers for my problem on the internet but didn't find something that helped, basically a need to have a ManyToOne Relationship between two classes, of which one of them has an EmbeddedId, I'm going to leave the code here and the error message that it gives (I'm using wildfly to run the server).

public class InventoryPK implements Serializable {

    @ManyToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "user_id")
    private Item itemId;

    @ManyToOne
    @JoinColumn(name="CD_EMPRESA")
    private Company company;
}

@Entity
@Table(name = "inventario", schema = "mxnextmob")

public class Inventory extends BaseModel {

    @EmbeddedId
    private InventoryPK id;

    @SequenceGenerator(schema = "mxnextmob", name = "inventory_sequence", sequenceName = "inventory_sequence", allocationSize = 1, initialValue = 1)
    @GeneratedValue(strategy = GenerationType.AUTO, generator = "inventory_sequence")
    private Integer inventory;

    @Column
    private BigDecimal quantity;

    @Column
    private BigDecimal weight;
}

public class Company extends BaseModel {

    @Id
    @SequenceGenerator(schema = "mxnextmob", name = "company_sequence", sequenceName = "company_sequence", allocationSize = 1, initialValue = 1)
    @GeneratedValue(strategy = GenerationType.AUTO, generator = "company_sequence")
    private Integer code;

    @Column
    private String name;

    @OneToMany(mappedBy = "company")
    private List<UserSeller> userSeller;

    @OneToMany(mappedBy = "id.company")
    private List<Inventory> inventories;
}

and the error is as follows:

service jboss.persistenceunit."mxnext-mobile.war#mxnextmobileDS": org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: br.com.maxiconsystems.mobile.model.Inventory.company in br.com.maxiconsystems.mobile.model.Company.inventory

Why are you adding in a sequence on an inventory field within Inventory, then using something else as its primary key? InventoryPK, as an IDClass or embeddedID cannot have relationship mappings within it. It must contain the basic mappings (values) that make up what uniquely identifies your Inventory, which could be backed by foreign key columns in the table. If you are looking for examples and tutorials, look up JPA derived IDs. But with this table setup, seems like you should just be using the inventory column as the ID - how do you plan to look up and reference Inventory? — Chris, Feb 04 '22 at 14:48

score 0 · Accepted Answer · answered Feb 04 '22 at 15:00

There are a few ways to map what you seem to have as a table, but I'd recommend Inventory be changed to something like:

public class Inventory extends BaseModel {
  @Id
  @SequenceGenerator(schema = "mxnextmob", name = "inventory_sequence", sequenceName = "inventory_sequence", allocationSize = 1, initialValue = 1)
  @GeneratedValue(strategy = GenerationType.AUTO, generator = "inventory_sequence")
  private Integer inventory;

  @Embedded
  private InventoryPK alternateKey;

  @Column
  private BigDecimal quantity;

  @Column
  private BigDecimal weight;
}

This allows you to use the inventory Integer as its primary key; this simplifies any future references you may need to add to Inventory, as foreign keys would be required in JPA to reference all its ID columns.

JPA Mapping @EmbeddedId with ManyToOne relationship

1 Answers1