Partial Update with association flushes changes too early - eclipselink [DATAREST-722]

Mathias D opened DATAREST-722 and commented

I am having a problem with partial updates in spring data rest using eclipselink as the JPA-provider.

From the description the issue seems to be related to DATAREST-441 - but I decided to create a separate issue for it because I am not sure if it is really the same issue.

Please find a reproduction project here:
https://github.com/mduesterhoeft/spring-data-rest-partial-update-issue/tree/jpa_with_eclipselink

I am having a simple entity defined like this:

public class Person {

    @GeneratedValue
    @Id
    private Long id;

    private String name;

    @ManyToOne
    @JoinColumn(name = "CHILD_ID")
    private Child child;
}

In a RepositoryEventHandler I try to determine if the name changed and execute some logic if it changed - PersonRepositoryEventHandler

@RepositoryEventHandler
@Component
public class PersonRepositoryEventHandler {

...

    @HandleBeforeSave
    public void compareName(Person newPerson) {
        entityManager.detach(newPerson);

        Person oldPerson = personRepository.findOne(newPerson.getId());

        if (oldPerson.getName().equals(newPerson.getName())) {
            //some logic here
        }
    }
}

If I send in the following payload the old and new name in the event handler actually differ. Also from the logging output I can see that the BeforeSave handler method is invoked first and the update of the name field follows after that - so this works as expected.

{"name":"newName"}

When I update the association to the child in the same request I see a different behaviour:

1. update statement updating the name field is issued (this is already happening before RepositoryEntityController#patchItemResource is invoked - so it happens during JSON deserialization)
2. the BeforeSave handler method is invoked (here old and new name carry the same value already and I cannot determine if it has been changed)
3. the update statement to update the child association is issued.

{
  "name":"newName",
   "child":"http://localhost/children/7"
}

My example project has a test for both cases - see com.example.PersonResourceTest

The repository also contains the example project using hibernate - as I said this works fine - https://github.com/mduesterhoeft/spring-data-rest-partial-update-issue/tree/jpa_with_hibernate

With the current situation I cannot reject certain updates in BeforeSave handlers and validators

Affects: 2.4.1 (Gosling SR1)

Reference URL: https://github.com/mduesterhoeft/spring-data-rest-partial-update-issue/tree/jpa_with_eclipselink

3 votes, 4 watchers