Is there a helper to know whether a property has been loaded by Hibernate?

问题

I need a helper to know whether a property has been loaded as a way to avoid LazyInitializationException. Is it possible?

@Entity
public class Parent {
    @OneToMany
    private List<Child> childList;
}

@Entity
public class Child {

}

"select distinct p from Parent p left join fetch p.childList";

// Answer goes here
// I want to avoid LazyInitializationException
SomeHelper.isLoaded(p.getChildList());

回答1:

There are two methods, actually.

To find out whether a lazy property has been initialized you can invoke Hibernate.isPropertyInitialized() method with your entity instance and property name as parameters.

To find out whether a lazy collection (or entity) has been initialized (like in your example) you can invoke Hibernate.isInitialized() with collection (entity) instance as parameter.

回答2:

According to the documentation for Hibernate 5.4

Hibernate API

boolean personInitialized = Hibernate.isInitialized(person);

boolean personBooksInitialized = Hibernate.isInitialized(person.getBooks());

boolean personNameInitialized = Hibernate.isPropertyInitialized(person, "name");

JPA

In JPA there is an alternative means to check laziness using the following javax.persistence.PersistenceUtil pattern (which is recommended wherever possible).

PersistenceUtil persistenceUnitUtil = Persistence.getPersistenceUtil();

boolean personInitialized = persistenceUnitUtil.isLoaded(person);

boolean personBooksInitialized = persistenceUnitUtil.isLoaded(person.getBooks());

boolean personNameInitialized = persistenceUnitUtil.isLoaded(person, "name");

来源：https://stackoverflow.com/questions/1589144/is-there-a-helper-to-know-whether-a-property-has-been-loaded-by-hibernate

标签

java

hibernate

lazy-loading

helper