[hibernate-issues] [Hibernate-JIRA] Created: (HHH-2935) Cascading save on OneToMany causes not null constraint violation on child table

[Aaron Luchko (JIRA)]

Cascading save on OneToMany causes not null constraint violation on child table
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                 Key: HHH-2935
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2935
             Project: Hibernate3
          Issue Type: Bug
    Affects Versions: 3.2.1
         Environment: hibernate-3.2.1, hibernate-annotations-3.2.1
            Reporter: Aaron Luchko
         Attachments: saveNull.zip

When defining a OneToMany relationship, controlled by the parent, and not nullable by the child, there's an issue when trying to insert the initially created columns.

With a schema attached as thus

public class Parent {
...
	@OneToMany(targetEntity = Child.class, cascade = { CascadeType.ALL })
	@Cascade( { org.hibernate.annotations.CascadeType.SAVE_UPDATE,
			org.hibernate.annotations.CascadeType.DELETE_ORPHAN })
	@JoinColumn(name = "parent_child")
	public List<Child> getChildren() {
		return children;
	}
}

public class Child{
...
	@ManyToOne
	@JoinColumn(name = "parent_child", insertable = false, updatable = false, nullable=false)
	public Parent getParent() {
		return parent;
	}
}


And running a section of code such as this

		Session session = HibernateUtil.getSession();
		session.beginTransaction();
		Parent parent = new Parent();
		int times = 2;
		List<Child> children = new ArrayList<Child>(times);
		for (int i = 0; i < times; i++) {
			Child child = new Child();
			children.add(child);
			child.setParent(parent);
		}
		parent.setChildren(children);
		session.save(parent);
		session.getTransaction().commit();


Hibernate attempts to run the following series of queries

select child_.id from Child child_ where child_.id=?
select child_.id from Child child_ where child_.id=?
insert into Parent (id) values (?)
insert into Child (id) values (?)
insert into Child (id) values (?)
update Child set parent_child=? where id=?
update Child set parent_child=? where id=?

The problem is that in initial batch inserting the two children fails violating the not null constraint before the update can assign a value to parent_child. 

I've reproduced this with postgresql and mysql (after setting the dialect to org.hibernate.dialect.MySQLInnoDBDialect, MyISAM doesn't catch the constraint violation).

As a workaround one can simply leave off the nullable=false.

I've attached a full testcase.

thanks,
Aaron

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