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 Post subject: EAGER null expectation issue
PostPosted: Tue Oct 10, 2017 5:20 am 
Newbie

Joined: Mon Oct 09, 2017 10:30 am
Posts: 1
Hello everyone,

I'm a bit new to Hibernate and I just wanted to ask a few questions about an issue I'm currently encountering.

To give a bit of a setting, I have a CUSTOMER entity that has a column called UPDATED_BY which is referenced to another table called USER.
@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = COLUMN_NAME_UPDATED_BY)
@Cascade(value = CascadeType.DETACH)
protected MyUser updatedBy;



When I try to execute the EntityManager.find() to fetch a CUSTOMER, there are customers with UPDATED_BY values that are not existing in the USER table (which I expect). This would then result to a null CUSTOMER entity returned by the find() method as explained by this message

DEBUG [org.hibernate.jpa.spi.AbstractEntityManagerImpl] (default task-21) HHH015013: Returning null (as required by JPA spec) rather than throwing EntityNotFoundException, as the entity does not exist
(Note: In which I tried to execute the query made by hibernate which actually returned a result of Customer but I assume that since update_by has no value, it returned the customer as a whole to be null)

With this, I wanted to know if there is a way to handle this by giving the UPDATED_BY column a "default" value when its current value(not null) does not actually exist in the USER table. Or if there are other better way to handle it instead. Also, I wanted to ask how this behavior actually works because it seems to me that when a child of parent is null and a find() is requested, the parent as a whole will be returned null.

All help would be greatly appreciated!
Please ask me you need more information about the issue.


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 Post subject: Re: EAGER null expectation issue
PostPosted: Wed Oct 11, 2017 9:14 am 
Hibernate Team
Hibernate Team

Joined: Thu Sep 11, 2014 2:50 am
Posts: 1638
Location: Romania
Quote:
there are customers with UPDATED_BY values that are not existing in the USER table (which I expect)


Sounds like a bad DB design you have there.

Since you said you were new to Hibernate, I expect you read the User Guide fully, right? If you did, you might have bumped into the @NotFound annotation to help you with this task.

Anyway, if you read the docs, you'll find solutions to other issues as well.

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If you liked my answer, you are going to love my High-Performance Java Persistence book and my blog as well.


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