[h2] Spring Boot Persistable<ID> interface behaviour: when testing with in-memory H2, no DataIntegrityViolationException is thrown when duplicated instance is saved, and "isNewObject" always set to "true"

[w***@gmail.com]

I submitted this issue at:

https://github.com/h2database/h2database/issues/1391


and redirected here.



In Spring, there is an interface
"org.springframework.data.domain.Persistable<ID>", which helps to mark the
"insertability/updatibility" of an entity. It requires the implementation
of two methods:

public interface Persistable<ID extends Serializable> extends Serializable {


/**
* Returns the id of the entity.
*
* @return the id
*/
ID getId();


/**
* Returns if the {@code Persistable} is new or was persisted already.
*
* @return if the object is new
*/
boolean isNew();
}

If is new, the object should be persisted; otherwise the DB should update
it.

Usually, we use this snippet to implement it:

@Transient
private boolean isNewObject;


@Override
public boolean isNew() {
return isNewObject;
}

We change `isNewObject` to change the behavior of DB. `isNewObject` to the
behavior of DB.

Why we need it? Because we want to first save, then if there was some
duplication, we catch an
DataIntegrityViolationException
and change `isNewObject()` to `false` and `save()` again, then the update
will be performed, instead of doing a full-table "select" (exist() check,
etc) before saving.


When testing in PostgreSQL, it works; but with in-memory H2, there is no
exception thrown, and `isNew`, after persisting any object, will be changed
to "true".


Is this interface taken into consideration in H2? I ask to confirm; if is
not, I will try to use PostgreSQL(the real DB engine) in my testing,
although I want to use H2 in-memory DB when doing a minimal integration
tests because it is supposed to be faster.