How do I disable Hibernate foreign key constraint on a bidirectional association?

Question

I am trying to disable the foreign key constraint being generated on my bidirectional association. I have managed to do this for all my unidirectional associations, but for some reason it is not working here.

I do know about the bug with ContraintMode.NO_CONSTRAINT that was recently fixed in Hibernate 5.x, and I am running the latest Hibernate 5.2.6.

My annotations presently look like this:

class Parent {
  @OneToMany(mappedBy="parent", cascade=CascadeType.ALL, orphanRemoval=true)
  @OrderColumn(name="childIndex")
  public List<Child> getChildren() {
    return children;
  }
}

class Child {
  @ManyToOne(optional=false)
  @JoinColumn(name="parent", foreignKey = @ForeignKey(value = ConstraintMode.NO_CONSTRAINT))
  public Parent getParent() {
    return parent;
  }
}

But despite NO_CONSTRAINT, Hibernate is still creating the foreign key constraint on child.parent -> parent.id.

Is there something additional I need to do to suppress the foreign key for the bidirectional case?

Thanks!

Cosmogony

Answer 1

This is known issue in Hibernate, see https://hibernate.atlassian.net/browse/HHH-8805

Solution is to add @org.hibernate.annotations.ForeignKey(name = "none") on the mapped side.

class Parent {

  @OneToMany(mappedBy="parent", cascade=CascadeType.ALL, orphanRemoval=true)
  @OrderColumn(name="childIndex")
  @org.hibernate.annotations.ForeignKey(name = "none")
  public List<Child> getChildren() {
    return children;
  }

}

Note: Prefer the JPA 2.1 introduced javax.persistence.ForeignKey instead. The native annotation is deprecated.

Serous

The Note given in this answer is wrong. javax.persistence.ForeignKey is what's used in the OP. It does not work, and it cannot be applied to a field. – Tyishatyke

@org.hibernate.annotations.ForeignKey is deprecated now, is there different solution? – Welcome

@KonradDrozd If you look at the issue mentioned above, it seems that the issue has been fixed (using @JoinColumn(foreignKey = @ForeignKey(ConstraintMode.NO_CONSTRAINT))) in Hibernate version 5.3.3 and 5.4.x. I haven't tried it myself, maybe you can give it a try. – Serous

@BustanilArifin It works but the IDE shows this warning"The type ForeignKey is deprecated". – Abattoir

Isn't there any solution to just disable foreign key auto generation only during testing through configuration? – Mundane

Answer 2

Addition to the @Bustanil Arifin answer:

You can combine @OneToMany and @javax.persistence.ForeignKey in next way:

class Parent {

  @OneToMany(cascade=CascadeType.ALL, orphanRemoval=true)
  @JoinColumn(name = "parent", foreignKey = @javax.persistence.ForeignKey(name = "none"))
  public List<Child> getChildren() {
    return children;
  }

}

Durfee

This isn't a suitable solution when using a mappedBy association (where the physical foreign key is stored on the other table); you'll get errors like: "Associations marked as mappedBy must not define database mappings like @JoinTable or @JoinColumn". And Hibernate will try to generate a column where it shouldn't. – Lathan