CODEWITHSUNDEEP
ormjpaentitynullpointerexceptioneclipselink
LeonS
LeonS

Reputation: 2714

Eclipselink - ID after persisting is still null

I've got a problem to persist an Entity and to get the id after the persist happened. I can see that the data was created in the database, with the right id, but the id is still null at the object.

Heres my entity:

@Entity
public class Bookmark {

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

private String name;

@Column(nullable = false)
@Temporal(TemporalType.DATE)
private Date createdAt;

@ManyToOne
private Page page;

@ManyToOne
private Color color;

@ManyToOne
private User user;

...
..

And here is my Code where I Create the Entity:

//init bookmark from json basic data
 Bookmark bookmark = new Bookmark(currentUser,page);

 bookmark.setName(name);
 bookmark.setColor(color);

 //set User relationship for the bookmark
 currentUser.getBookmarks().add(bookmark);

 //save the altered entities
 tx.begin();
 em.merge(currentUser);
 em.persist(bookmark);
 tx.commit();


 //Build the response
 System.out.println("uriInfo:"+uriInfo+ "bookmark:"+bookmark);
 URI bookmarkUri = uriInfo.getAbsolutePathBuilder().path(bookmark.getId().toString()).build();

I'm getting a nullpointer Exception at the last line because getId() results in null. How can i avoid that?

Upvotes: 3

Views: 2642

Answers (2)

LeonS
LeonS

Reputation: 2714

I fixed the problem. The root of the problem is the order of the commands to persist the bookmark. This is the right order:

em.persist(bookmark);
em.merge(currentUser);

So first of all you have to persist the entity and after that you can merge the entity of the relationships of that entity.

Upvotes: 2

Tim H
Tim H

Reputation: 338

I'm not familiar with the Identity PK generation strategy, perhaps you should add @ReturnInsert to your @Id column, to force the PK to be returned on insert statements.

Upvotes: 1

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