Restriction error in relationship Onetomany Hibernate

Question

I’m getting error in the Onetomany relationship when I try to persist an entity.

Error:

org.postgresql.util.PSQLException: ERROR: null value in column "book_url_id" violates not-null constraint Detalhe: Failing row contains (2, name, pattern, temp, type, null).

Bookurl.java:

@Builder
@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name = "book_urls")
public class BookUrlEntity implements Serializable {

    private static final long serialVersionUID = 1216319313385073856L;

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

    @NotNull
    private String url;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "bookUrl")
    private Set<BookUrlParameterEntity> parameters;
}

Bookurlparameterentity.java

@Builder
@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name = "book_url_parameters")
public class BookUrlParameterEntity implements Serializable{

    private static final long serialVersionUID = -1388929732076588240L;

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

    @NotNull
    @Column(name = "variable_name")
    private String variableName;

    @NotNull
    @Column(name = "variable_type")
    private String variableType;

    @NotNull
    @Column(name = "variable_pattern")
    private String variablePattern;

    @Column(name = "variable_temp_value")
    private String variableTempValue;

    @ManyToOne
    @JoinColumn(nullable = false, updatable = false, insertable = true)
    private BookUrlEntity bookUrl;
}

I’m trying to persist that way:

BookUrlEntity book = BookUrlEntity.builder().url("www.com.br").build();
BookUrlParameterEntity p1 = BookUrlParameterEntity.builder()
        .variableName("asd")
        .variablePattern("asd")
        .variableType("asda")
        .build();
BookUrlParameterEntity p2 = BookUrlParameterEntity.builder()
        .variableName("asd")
        .variablePattern("asd")
        .variableType("asdw")
        .build();
BookUrlParameterEntity p3 = BookUrlParameterEntity.builder()
        .variableName("asd")
        .variablePattern("asd")
        .variableType("asdq")
        .build();
Set<BookUrlParameterEntity> params = new HashSet<BookUrlParameterEntity>();
params.add(p1);
params.add(p2);
params.add(p3);
book.setParameters(params);

bookUrlRepository.save(book);

I’ve looked elsewhere about relationships, but it’s still a little confusing to me, which I’m starting with Spring, Hibernate.

Answer 1

In the code you added we can see the problem, the objects P1, P2 and P3 are in the field bookUrl null. Add the object bookvariables P1, P2 and P3. would be something like:

BookUrlParameterEntity p1 = BookUrlParameterEntity.builder()
        .variableName("asd")
        .variablePattern("asd")
        .variableType("asda")
        .bookUrl(book)
        .build();

The same with P2 and P3.

As you are using Lombok, and have a bidirectional relationship you need to delete the field bookUrl in class Bookurlparameterentity with this annotation:

@EqualsAndHashCode(exclude="bookUrl")

For more information: Documentation @Equalsandhashcode