如何在一次打开session中删除具有一级缓存和JPA的实体？

Question

In my persistence layer i have remove method that will remove the entities in removed state and EntitySession to commit the changes.

• The EntitySession

transaction = entityManager.getTransaction();

• The remove method

    public BehindCacheBuilder<R, V> remove(Object object) {
        entityManager.remove(object);
        return this;
    }

• And committing the transaction

transaction.commit();

But when i execute the method nothing will remove from datasource.

Answer 1

Like any write-behind cache the Persistence context requires flushing (in your case committing, which is different than flushing) in order to synchronize the in-memory persistence state with underlying datasource.

Thus firstly make sure your entities that you want to remove be present in Managed state from first place then try to remove to change the state for delating the entity after flushing (committing).

    public BehindCacheBuilder<R, V> remove(Class<?> type, Object object) {
        entityManager.remove(entityManager.find(type, object));
        return this;
    }

Which in here we bring the entity that we want to remove to Managed state.