For a years in a project i used from hibernate 4.3.11.Final and spring 4.3.1.RELEASE to maniuplating and persisting objects. Newly i migrated to hibernate 5.2.10.Final and encountered a problem that describe it. I have two domain class as you can see below:
public class Post extends BaseEntity<Long> {
private String title;
private Set<PostComment> comments = new HashSet<>(0);
// getters and setters removed for brevity
}
public class PostComment extends BaseEntity<Long> {
private Post post;
private String descripton;
// getters and setters removed for brevity
}
public abstract class BaseEntity<T> implements Serializable {
private T id;
}
and these are hibernate mapping files:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="" table="tbl_post">
<id name="id" type="long" >
<column name="ID" />
<generator class="sequence" >
<param name="sequence">RGH.SEQ_POST</param>
</generator>
</id>
<property name="title" column="title" type="string" not-null="true" />
<set name="comments" inverse="true" cascade="save-update,merge">
<key>
<column name="post_id" not-null="true" />
</key>
<one-to-many class="com.rgh.PostComment" />
</set>
</class>
</hibernate-mapping>
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="" table="tbl_post_comment">
<id name="id" type="long" >
<column name="ID" />
<generator class="sequence" >
<param name="sequence">RGH.SEQ_POST_COMMENT</param>
</generator>
</id>
<property name="descripton" column="descripton" type="string" not-null="true" />
<many-to-one name="post" column="post_id" entity-name="com.rgh.Post" not-null="true" />
</class>
</hibernate-mapping>
In the PostService class exists two methods that one of theme persists Post entity and it's PostComment's and another save the Post entity and logs count of it's PostCommment's.
@Service
public class PostService {
@Autowired
private PostRepository repo;
@Autowired
private PostCommentRepository commentRepo;
@Transactional
public Long save() {
Post post = new Post();
post.setTitle("sample post");
repo.save(post);
Set<PostComment> postComments = new HashSet<>();
for (int i = 0 ; i < 3 ; i++) {
PostComment postComment = new PostComment();
postComment.setPost(post);
postComment.setDescription("description " + i);
commentRepo.save(postComment);
}
return post.getId();
}
@Transactional
public int saveAndGetDetailsCount(Post entity) {
entity.setTitle(entity.getTitle() + " updated!");
repo.save(entity);
Post post = repo.loadById(entity.getId());
System.out.println(post.Comments().size());
return post.Comments().size();
}
}
Both of PostRepository and PostCommentRepository are extended from GenericRepository that you can see it below:
@Repository
public class PostRepository extends GenericRepository<Post, Long> {
@Override
protected Class<Post> getDomainClass() {
return Post.class;
}
}
@Repository
public class PostCommentRepository extends GenericRepository<PostComment, Long> {
@Override
protected Class<PostComment> getDomainClass() {
return PostComment.class;
}
}
@Repository
public abstract class GenericRepository<T extends BaseEntity,PK extends Serializable> {
protected Class<T> domainClass = getDomainClass();
@Autowired
private SessionFactory sessionFactory;
public Session getSession() {
try {
return sessionFactory.getCurrentSession();
} catch (Exception e) {
}
return sessionFactory.openSession();
}
public PK save(T Entity) {
Session session = getSession();
if(entity.getId() == null) {
session.save(entity);
}
else {
entity = (T)session.merge(entity);
session.update(entity);
}
return entity.getId();
}
public T loadByEntityId(PK entityId) {
Session session = getSession();
return (T) session.get(domainClass.getName(), entityId);
}
}
Everything is working fine when i call save method and then call saveAndGetDetailsCount it updates the entity and then executes select... query to load Post entity and then logs 3 and post comments.
But after i migrated to hibernate 5.2.10.Final and applied these changes:
@Entity
@Table(schema = "RGH", name = "TBL_POST")
@SequenceGenerator(name = "sequence_db", sequenceName = "RGH.SEQ_POST", allocationSize = 1)
public class Post extends BaseEntity<Long> {
@Column
private String title;
@OneToMany(mappedBy = "post", fetch = FetchType.LAZY)
@Cascade(value = { CascadeType.SAVE_UPDATE, CascadeType.MERGE })
private Set<PostComment> comments = new HashSet<>(0);
// getters and setters removed for brevity
}
@Entity
@Table(schema = "RGH", name = "TBL_POST_COMMENT")
@SequenceGenerator(name = "sequence_db", sequenceName = "RGH.SEQ_POST_COMMENT", allocationSize = 1)
public class PostComment extends BaseEntity<Long> {
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "POST_ID", nullable = false)
private Post post;
@Column
private String descripton;
// getters and setters removed for brevity
}
public abstract class BaseEntity<T> implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "sequence_db")
private T id;
}
and in then GenericRepository i used EntityManager to get Session class as you can see below:
@Repository
public abstract class GenericRepository<T extends BaseEntity,PK extends Serializable> {
protected Class<T> domainClass = getDomainClass();
/* changed */
@PersistenceContext
private EntityManager em;
public Session getSession() {
/* changed */
return em.unwrap(Session.class);
}
public PK save(T Entity) {
Session session = getSession();
if(entity.getId() == null) {
session.save(entity);
}
else {
entity = (T)session.merge(entity);
session.update(entity);
}
return entity.getId();
}
public T loadByEntityId(PK entityId) {
Session session = getSession();
return (T) session.get(domainClass.getName(), entityId);
}
}
Now, the problem is that, when i run previous method calls, in the saveAndGetDetailsCount, hibernate does not execute select... query and logs 0 as comments count.
I wondered why this happened.
UPDATE
Maybe you ask why i didn't used from EntityManager insteadof Session, i have some limitation to use EntityManager.
UPDATE
When i call the saveAndGetDetailsCount, the entity parameter contains only id and title and in the next lines as you can see i want to load comments field and get it's size.
