Hibernate, How can I detach and/or get data only on demand?

Question

I have an entity setup like this:

@Entity
@Table(name = "APP", uniqueConstraints = @UniqueConstraint(columnNames = "APP_KEY"))
public class Application implements java.io.Serializable {
    ...
    @OneToMany(fetch = FetchType.LAZY)
    @JoinColumn(name = "application_Id", referencedColumnName = "application_Id")
    private Set<Document> documents = new HashSet<Document>(0);
}

Now, in some situations I don't want the list of documents to be returned. However when I serialize this object the "getDocuments()" method will be called.

There will not be an active transaction at this time, so I don't want one of those "no session" errors. I just want to ignore it and have the getDocuments() method return empty, not throw an exception and not try to fetch more data.

I would go for setting empty Set manually after detachment but before serialization. — zbig, Jul 18 '14 at 09:35

score 0 · Answer 1 · edited May 23 '17 at 10:32

0

Take a look at the FetchGroup capability ref:

Take a look at the jpql fetch join's...

Select e from Employee e join fetch e.phones p where p.areaCode = '613'

This was covered for a similar question here: How to properly express JPQL "join fetch" with "where" clause as JPA 2 CriteriaQuery?

edited May 23 '17 at 10:32

Community

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answered Jul 17 '14 at 19:13

Craig Taylor

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I don't think this is what Triton Man is asking for. He doesn't want to fetch but don't want `LazyInitializationException` either. – zbig Jul 18 '14 at 09:29

score 0 · Answer 2 · answered Oct 19 '16 at 16:18

I do not know your serialization setup, however:

If you are using Jackson, you can use this : https://github.com/FasterXML/jackson-datatype-hibernate which works quite nicely.
If you have a manual serialization setup, you should probably not be calling methods directly, without prior knowledge of their initialization status. What you could do is use something like Hibernate.isInitialized(object.Method) https://docs.jboss.org/hibernate/orm/5.2/javadocs/org/hibernate/Hibernate.html#isInitialized-java.lang.Object-

Hibernate, How can I detach and/or get data only on demand?

2 Answers2