ManyToOne Mapping throws exception "com.sap.olingo.jpa.metadata.core.edm.mapper.exception.ODataJPAModelException: Error when creating Referential Constraints"

I am trying to make a simple demo application using this library. I get the above error when using a ManyToOne mapping between my entities.

Entity BeerRating

  @Id
  @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "BEER_RATING_ID_GENERATOR")
  @Column(name = "ID", nullable = false, precision = 10)
  private BigDecimal id;

  @ManyToOne
  @JoinColumn(name = "BEER_ID", referencedColumnName = "ID")
  private Beer beer;

Entity Beer

@Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "BEER_ID_GENERATOR")
    @Column(name = "ID", nullable = false, precision = 10)
    private BigDecimal id;

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

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

[wzagrajcz]

Hello, I had similar issue and Your solution helped me. Thanks a lot.

However, I wanted to have my relationship bidirectional. So keeping the same entities as in original post I would like to use both

ODataDemo.svc/BeerRatings?$expand=Beer and ODataDemo.svc/Beers?$expand=BeerRating The first one is working perfectly. To achieve the second I added to the Beer something like that

@OneToMany(mappedBy = "beer")
private List<BeerRating> beerRating = new ArrayList<>();

However it does not work - I got error of null code with error message Element BeerId does not correspond to an element in the query result. Do You happen to know what I’m doing wrong? Error message does not tell much to me especially since beerId located in BeerRating have @EdmIgnore annotation.

Thanks

[wog48]

Hello,

in opposite of JPA the JPA Processor needs, as of now, the join column as attribute. You need add the following to BeerRating:

  @EdmIgnore
  @Column(name = "BEER_ID", precision = 10, insertable = false, updatable = false)
  private BigDecimal beerId;

Now the error is gone and BeerId wont appear as property in the metadata document.