CODEWITHSUNDEEP
javadatabasehibernate
Nick
Nick

Reputation: 729

Removing entities from Collection in hibernate

I'm trying to manually delete every entity that's in a collection on an entity. The problem is, the entities don't get deleted from the database, even though they get removed from the collection on the task.

Below is the code im using to achieve this:

public int removeExistingCosts(final DataStoreTask task) {

    int removedAccumulator = 0;
    Query query = entityManager.createNamedQuery(DataStoreCost.GET_COSTS_FOR_TASK);
    query.setParameter(DataStoreCost.TASK_VARIABLE_NAME, task);


    try {

        List costsForTask = query.getResultList();
        for(Object cost : costsForTask) {
            task.getCosts().remove(cost);
            removedAccumulator++;
        }

    } catch (NoResultException e) {
        logger.debug("Couldn't costs for task: {}", task.getId());
    }

    entityManager.flush();
    entityManager.persist(task);

    return removedAccumulator;
}

Any ideas?

P.S the collection is represented as:

@OneToMany(targetEntity = DataStoreCost.class, mappedBy = "task", cascade = CascadeType.ALL)
private Collection<DataStoreCost> costs;

Cheers.

Upvotes: 2

Views: 840

Answers (2)

Joeri Hendrickx
Joeri Hendrickx

Reputation: 17445

It's not deleting the entity, because it doesn't know if something else is referring to it.

You need to enable delete orphan. In jpa2, use the orphanRemoval attribute. If you're using hibernate annotations, use CascadeStyle delete orphan.

Upvotes: 1

Robe Elckers
Robe Elckers

Reputation: 977

I think you need to explicitly remove the Cost entity via the entityManager. When you remove the Cost from the Tasks cost list you actually only remove the reference to that instance. It does not know that that particular Cost will not be used anywhere else.

Upvotes: 1

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