How to cause related entities to update when base entity is

[a_titov82]

I have two entities:

public class Employee {
...
 @ManyToOne
 public Organization getPlaceOfWork() {
 return placeOfWork;
 }
 public void setPlaceOfWork(Organization placeOfWork) {
 this.placeOfWork = placeOfWork;
 if(placeOfWork!=null){
 placeOfWork.getEmployees().add(this);
 }
 }

}

public class Organization {
...
 @OneToMany(fetch=FetchType.EAGER, mappedBy="placeOfWork")
 public Collection<Employee> getEmployees() {
 return employees;
 }
 public void setEmployees(Collection<Employee> employees) {
 this.employees = employees;
 }
}

How can I cause Employees to be set their placeOfWork to null when Organization is removed (like database cascade)? And what should I do, if I want to delete Employees when Organization is removed?

[epbernard]

1. is not possible this is not how you would work in a object model (wo persistence)
2. can be done through cascade=CascadeType.REMOVE on the @OneToMany association

[a_titov82]

1. is not possible this is not how you would work in a object model (wo persistence)

But how can I provide reference integrity? If placeOfWork cannot be set to null automatically then it is possible to have references to non-existence objects. Especially in MySql database with MyISAM engine which does not support foreign keys...

[epbernard]

do a query that load the associated object and remove them

[a_titov82]

do a query that load the associated object and remove them

But where should I do that? If the base entity is removed by cascade, what then? The only way I found is to create an annotated method which will be called when entity is removed. But it must be coded manually and this is error prone, I think.

[epbernard]

Looking at your specific problem, an employee without organization is not an employee anyway, it should be removed ;-)