Hibernate/JPA: How to force implicit joins to use LEFT OUTER JOINS

Question

There is a class Offer that has optional relationship to class Article. So that some offers article property holds a null value.

If i use the following statement, everything works fine. I got all offers, even those that have no article.

SELECT o FROM Offer o 
         LEFT OUTER JOIN o.article a 
         LEFT OUTER JOIN o.vendor v 
         WHERE v.number = '0212' OR a.nummer = '123456'

If i change the statement to:

SELECT o FROM Offer o 
         LEFT OUTER JOIN o.article a 
         LEFT OUTER JOIN o.vendor v 
         WHERE v.number = '0212' OR o.article.nummer = '123456'

I got only these offers having articles different from NULL. That is because the notation for implicit joins (o.article.nummer) forces an inner join.

Is there a possibility to force left outer joins to implicit joins (annotation driven or something else)? If there is a chance i could use a short form like this:

SELECT o FROM Offer o 
         WHERE v.number = '0212' OR o.article.nummer = '123456'

Answer 1

You can try putting @Fetch(FetchMode.JOIN) on the Article property. This is a Hibernate annotation, however.

import org.hibernate.annotations.Fetch;
import org.hibernate.annotations.FetchMode;

//...

@ManyToOne
@Fetch(FetchMode.JOIN)
Article article;