How solve javax.persistence.EntityNotFoundException with JPA (not by using @NotFound)

Question

We are using JPA to load some stuff from a database. Some entities may have optional relationships between them, e.g.

@Entity
public class First {
    ....
    @OneToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH, CascadeType.DETACH})
    @JoinColumns(value = {
        JoinColumn(name = "A_ID", referencedColumnName = "A_ID", insertable = false, updatable = false), 
        JoinColumn(name = "B_ID", referencedColumnName = "B_ID", insertable = false, updatable = false)})
    private Second second;

When this association is present in the database, everything is working fine. When it's not, I'm getting a javax.persistence.EntityNotFoundException
What I want is instead of the exception to have this field as NULL if the association is not present.

I have tried several different things, e.g. using the optional=true in the relationship annotation (which btw is the default option), putting it as Nullable, etc. Nothing seems to do the trick, it seems like all these options are being ignored.

I found a lot of links mentioning this very same problem (and some questions here in stackoverflow) but in all of them the suggestion is to use the @NotFound annotation from Hibernate. But we do NOT want to have any dependencies to Hibernate (we want to keep everything pure JPA).

Does any of you guys know any other way to solve this?

Many thanks for all your help!

Yes, become part of the *expert* group that writes the JPA spec and hit them in the head until it's added... There's no 'JPA' way to do what you want. JPA has only very basic features, if you want anything more complicated, you'll need to use Hibernate or any other ORM specific annotations/configuration. — Augusto, Sep 04 '12 at 10:52
if "second" is never null (as you say to one answer) then the FK to that related record is set (not null), and so it should always find the related object ... or at least does with the JPA impl I use. If "second" is null then it should just return "first.second" as null ... in the JPA impl I use it does. How "there is no JPA way" I don't get — Neil Stockton, Sep 04 '12 at 18:27
When I say "is never null", I mean that it either has a value (when there is smth in the db) or there is an exception (EntityNotFound). By default, the OneToOne annotation assumes optional=true, which works in most implementations of JPA, but not with the one we are using (Hibernate 3.6.4). The optimal thing would be to either upgrade to the latest version of Hibernate (in which I think they fixed this problem) or use a different implementation, but unfortunately none of these options is possible for our project! — Alex Ntousias, Sep 05 '12 at 11:30
Ok, thx for the clarification. So the issue is Hibernate-specific and not JPA (general) unlike what the previous commenter implied. Good luck — Neil Stockton, Sep 05 '12 at 12:12

score 7 · Answer 1 · answered Oct 23 '13 at 13:42

7

Below is an alternative solution for this problem. I had to build on top of an old database where the relations sometimes were corrupt. This is how I solved it by only using JPA.

@PostLoad
public void postLoad(){
    try {
        if(getObject() != null && getObject().getId() == 0){
            setObject(null);
        }
    }
    catch (EntityNotFoundException e){
        setObject(null);
    }
}

answered Oct 23 '13 at 13:42

Björn

1,583
1
13
28

Thank you so much for this suggestion. This doesn't break lazy loading like Hibernates @NotFound(action=NotFoundAction.IGNORE) does. Works with Join fetches too (only makes 1 extra query for the missing entity with id 0, instead of 1 extra query for every related object). – DeezCashews Mar 13 '14 at 12:46

score 2 · Answer 2 · edited Oct 18 '20 at 14:01

2

Try to add the parameter optional = true to your @OneToOne annotation.

edited Oct 18 '20 at 14:01

aboger

1,756
5
27
40

answered Sep 04 '12 at 17:35

Fabiano

41
1

1

Please read the description of the question more carefully...I have already tried that but it's not working! It's a bug with Hibernate (https://hibernate.onjira.com/browse/ANN-725), it ignores the `optional=true`. – Alex Ntousias Sep 05 '12 at 08:51

score 2 · Answer 3 · answered Apr 17 '15 at 08:45

I've met the same problem. It's not always reproducable, so I cannot test it, but here are some thoughts:

The instance of your Second class is deleted, while the instance of the First class does not know anything about that.

You need a way to let an instance of First know, when its instance of Second is deleted.

cascade option for removing does not help here.

You may try to use bidirectional relationship, when instance of First exists inside instance of Second. It let you update instance of First via instance of Second before removing second

Bidirectional relationship - is evil. I would suppose in your case, that First - is owner of Second. Don't allow any service delete your Second instance directly. Let service which works with instances of First remove instance of Second. In this case you may make the "second" field nullable first, than remove instance of Second via EntityManager.

You may get exception when execute queries and the 2nd level cache is enabled and query has a hint, which allows to cache its result. I would offer you get result of queries via the following method:

private List<?> getQueryResult(final Query query)
{
    try
    {
        return query.getResultList();
    }
    catch (EntityNotFoundException e)
    {
        return query.setHint("javax.persistence.cache.storeMode", CacheStoreMode.REFRESH).getResultList();
    }
}

If you work with entities via EntityManger, but not via queries, and you get exception because entity is cached, you may invalidate all entities of First in cache when you delete Second.

I'd like to discuss this solution, as I cannot test it and cannot make sute it works. If somebody tries, please let me know.

PS: if somebody has a unit test for hibernate, that reproduces this issue, could you please let me know. I wish to investigate it further.

I tested this solution. It works, so, my problem now is following: I have two Entities, A and B. A has one B while B has many A, so `@ManyToOne(fetch = FetchType.LAZY) private B b;` `@OneToMany private List list;` My DB has not foreign-key and in case A has a value not present in B table I want however take this value and print it on a view. How I can do? — carmelolg, Jan 27 '17 at 11:40

score 2 · Answer 4 · answered May 06 '18 at 09:54

2

It happens when you delete the associated entity id. In my case I had Product table depending upon Brand table. I deleted a row or an entity of brand id to which one of the product instance was depending upon.

answered May 06 '18 at 09:54

Dila Gurung

1,450
18
22

score 0 · Answer 5 · answered Sep 04 '12 at 11:33

0

What about adding a test in the correspondent entity class:

public boolean getHasSecond() {
    if (this.Second != null) {
        return true;
    } else {
        return false;
    }
}

Like this, you can check if the relation exists...

answered Sep 04 '12 at 11:33

Adrian

11

2

This is not possible. `second` is never null, that's the problem. JPA tries to load it from the db, and if it's not found, then it throws the exception...so this method will never execute! Besides, how can you check if something exists if you don't actually try to load it from the db? – Alex Ntousias Sep 04 '12 at 12:30

score -1 · Answer 6 · edited Jul 08 '20 at 03:55

-1

Try to use cascade=CascadeType.ALL in @OneToMay(******).

edited Jul 08 '20 at 03:55

jizhihaoSAMA

10,685
9
18
36

answered Jul 07 '20 at 08:50

win zaw Oo

1

This does not provide an answer to the question. Once you have sufficient [reputation](https://stackoverflow.com/help/whats-reputation) you will be able to [comment on any post](https://stackoverflow.com/help/privileges/comment); instead, [provide answers that don't require clarification from the asker](https://meta.stackexchange.com/questions/214173/why-do-i-need-50-reputation-to-comment-what-can-i-do-instead). - [From Review](/review/low-quality-posts/26609739) – bartektartanus Jul 07 '20 at 09:31

How solve javax.persistence.EntityNotFoundException with JPA (not by using @NotFound)

6 Answers6

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