Hibernate @ManyToOne(fetch = FetchType.LAZY) ignored

Question

I have a lazy @ManyToOne column on Purchase defined as:

@ManyToOne(fetch = FetchType.LAZY)
Sale sale = null

However, when I load the entity from db, it gets directly loaded:

Purchase purchase = em.find(Purchase.class, id);
PersistenceUnitUtil unitUtil = em
        .getEntityManagerFactory()
        .getPersistenceUnitUtil();
System.err.println(unitUtil.isLoaded(purchase, "sale"));

This will return true even though the field should not yet be loaded.

What am I doing wrong?

(Hibernate 4.3.11.Final)

kan · Accepted Answer · 2017-08-24 08:25:38Z

3

Because it is nullable field. Hibernate cannot know if the value exists in the db or not, so it must query db to assign null or a value to the field.

answered Aug 24, 2017 at 8:25

kan

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4 Comments

Vojtěch Over a year ago

So what could I do to prevent this?

kan Over a year ago

Not so many options as I know. One way is "buildtime bytecode instrumentation". docs.jboss.org/hibernate/orm/3.3/reference/en/html/…

Vojtěch Over a year ago

So why this function is even there when it cannot never work? I even tried nullable = false with no effect.

kan Over a year ago

@Vojtěch The function works in some cicrumstances, e.g. when you are using the instrumentation. But it is not guaranteed, just "best effort".

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