CODEWITHSUNDEEP
javahibernatejpa
Kropius Dop
Kropius Dop

Reputation: 105

Hibernate detached entity i believe

I am kinda beginner when it comes to hibernate, but i have been dealing with a problem for several hours, and i need your help.

I have an application that manages articles, and each article is written by an author. What i want to do is to add an article to a database, with its author_id field being null, and only after that to update that field. However, hibernate refuses to update my entity in the database.

public <Article> void updateElement(Article entity) {
        EntityManager entityManager = createEntityManager();
        try {
            entityManager.getTransaction();
            entityManager.merge(entity);
            entityManager.getTransaction().commit();
        }
        catch(RuntimeException e ){
            entityManager.getTransaction().rollback();
        }
        finally {
            entityManager.close();
        }
    }

This is how i try to update the entry. I receive an Article as a parameter, for which i know for sure that it is in the database. And after that i try to do merge in order to update it. But i don't know if it the right approach. Please help me.

The article class:

@ToString
@AllArgsConstructor
@NoArgsConstructor
@Setter
@Getter
@Entity
@Table( name = "Article")
public class Article {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "article_id")
    private Integer id;

    @NotBlank
    @Column(name = "title")
    private String title;

    @NotBlank
    @Column(name = "publication_date")
    private Date publicationDate;

    @ManyToOne(cascade = CascadeType.ALL,fetch = FetchType.LAZY)
    @JoinColumn(name = "author_id")
    private Author author;

    @ManyToMany(fetch = FetchType.EAGER)
    @Enumerated(EnumType.STRING)
    @JoinTable(name = "article_tags",
                joinColumns = @JoinColumn(name = "article_id"),
                inverseJoinColumns = @JoinColumn(name ="tag_id"))
    private Set<Tag> tags = new HashSet<>();
}

and the author class

@NoArgsConstructor
@Setter
@Getter
@Entity
@Table(name = "Authors")
public class Author {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE,
            generator = "entity_id_seq")
    @Column(name = "author_id",updatable = false)
    private int id;

    @NotBlank
    @Column(name = "author_name")
    private String name;

    @OneToMany(mappedBy = "author",cascade = CascadeType.ALL,fetch = FetchType.LAZY)
    private Set<Article> writtenArticles = new HashSet<>();

}```

Upvotes: 0

Views: 44

Answers (1)

Yosef-at-Panaya
Yosef-at-Panaya

Reputation: 706

please begin your transaction and not only get the transaction: replace the

        entityManager.getTransaction();

by

        entityManager.getTransaction().begin();

Upvotes: 1

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