java - Hibernate PersistentSet remove() operation not working

Question

I've a Set in my Parent entity as below:

Class Parent {
 @OneToMany(mappedBy = parent, cascade = CasacadeType.ALL)
 Set<Child> children;
}

Class Child {
 @Column(nullable=false)
 @ManyToOne
 Parent parent;
}

Now event if I do a remove() operation on the Set for one of its element it doesn't actually get removed.

Answer 1

Your mapping should look like this:

public class Parent { 
    @OneToMany(mappedBy = parent, cascade = CasacadeType.ALL, orphanRemoval = true) 
    private Set<Child> children = new HashSet<>();
    
    public void removeChild(Child child) {
        children.remove(child);
        child.setParent(null);
    }
}

public class Child {
    @ManyToOne
    private Parent parent;
}

Because you have a bidirectional association you have to have both sides in-sync.

Therefore, it's good practice to call:

parent.removeChild(child);

This way, removeChild is going to remove the Child from the children Set and also set the Child parent association to null.