CODEWITHSUNDEEP
mysqlhibernatespring-bootjpa
user7307131
user7307131

Reputation:

JPA Hibernate bidirectional relation ends in null pointer

I have 2 entities: Version and Change log. A Version has N change Logs and a Change Log has one Version.

My Version entity looks like:

@Table(name="change_log_version")
@Entity
public class ChangeLogVersionEntity {

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

   @Column(name="version")
   private String version;

   @Column(name="date")
   private LocalDateTime date;

   @OneToMany(mappedBy = "version", cascade=CascadeType.ALL, fetch = 
   FetchType.EAGER)
   public List<ChangeLogEntity> changeLogEntities;

   public void addChangeLog(ChangeLogEntity changeLogEntity) {
      this.changeLogEntities.add(changeLogEntity);

      changeLogEntity.setVersion(this);
  }

...

}

My Change Log entity looks like:

@Table(name="change_log")
@Entity
public class ChangeLogEntity {

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

   @Column(name="description")
   private String description;

   @Column(name="added")
   private boolean isAdded;

   @Column(name="modified")
   private boolean isModified;

   @Column(name="deleted")
   private boolean isDeleted;

   @Column(name="public")
   private boolean isPublic;

   @Column(name="date")
   private LocalDateTime date;

   @ManyToOne(cascade=CascadeType.ALL, fetch = FetchType.EAGER)
   @JoinColumn(name = "version_id")
   private ChangeLogVersionEntity version;
  ...
 }

I am kinda new to hibernate and i am stuck in a null pointer by adding a change log to the version. What do i have to change to archive the relation?

Many thanks in advance so far :)

Upvotes: 1

Views: 400

Answers (1)

Simon Martinelli
Simon Martinelli

Reputation: 36173

That's because the changeLogEntites List is not initialized.

You should initialize it in the declaration

@OneToMany(mappedBy = "version", cascade=CascadeType.ALL, fetch =  FetchType.EAGER)
public List<ChangeLogEntity> changeLogEntities = new ArrayList<>();

Upvotes: 1

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