JPA entity relations are not populated after .persist()
- by Tomik
Hello, this is a sample of my two entities:
@Entity
public class Post implements Serializable {
@OneToMany(mappedBy = "post", fetch = javax.persistence.FetchType.EAGER)
@OrderBy("revision DESC")
public List<PostRevision> revisions;
@Entity(name="post_revision")
public class PostRevision implements Serializable {
@ManyToOne
public Post post;
private Integer revision;
@PrePersist
private void prePersist() {
List<PostRevision> list = post.revisions;
if(list.size() >= 1)
revision = list.get(list.size() - 1).revision + 1;
else
revision = 1;
}
So, there's a "post" and it can have several revisions. During persisting of the revision, entity takes a look at the list of the existing revisions and finds the next revision number. Problem is that Post.revisions is NULL but I think it should be automatically populated. I guess there's some kind of problem in my source code but I don't know where. Here's my "persistence" code:
Post post = new Post();
PostRevision revision = new PostRevision();
revision.post = post;
em.persist(post);
em.persist(revision);
em.flush();
I think that after persisting "post", it becomes "managed" and all the relations should be populated from now on.
Thanks for help!
(Note: public attributes are just for demonstration)
