JPA association without foreign key

Question

Is it possible to set up a ManyToOne association without JPA creating a foreign key in the database?

The tables are owned by another system and are populated asynchr

Answer 1

Add name="none" in javax.persistence.ForeignKey,

this worked for me.

foreignKey = @javax.persistence.ForeignKey(name="none",value = ConstraintMode.NO_CONSTRAINT)

Answer 2

The fact that ConstraintMode.NO_CONSTRAINT is ignored looks like a bug in Hibernate 4 due to be fixed in 5.

https://hibernate.atlassian.net/browse/HHH-8805

The comments on that and indeed this post here:

Multiple relationships with single mapping table without generating foreign keys by Hibernate

suggest adding the deprecated (hibernate rather than JPA) annotation

@ForeignKey( name = "none" )

to the relationship should work.

Answer 3

In Hibernate 4.3.X annotation field with @org.hibernate.annotations.ForeignKey( name = "none") worked for me.

But be carefull: in case of bidirectional relationships, you have to annotate two fields by mentionad annotation!!!