Hibernate Lazy Initialization exception even using Join Fetch in HQL queries

Question

I want to initialize a collection with lazy fetch mode and use Join Fetch in my queries but I some times(not always) face with lazy initialization exception ???

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: xxx.entity.Product.producerEntities, could not initilaize proxy - no session ...

for example this query:

"select p from Product p left join fetch p.producerEntities"

and my persistence class:

    class Product
    {
        Set<Producer> producerEntities = new HashSet<>();
        ....
        @OneToMany(fetch = FetchType.LAZY)
        @JoinColumn(name="pid")
        public Set<Producer> getProducerEntities(){
         return producerEntities;
         }
    ....

}

I don't understand what is the problem?

I know Angad Bansode, for clear I write fetch = FetchType.LAZY. — M2E67, Sep 06 '18 at 06:15
can you add an example of when that exception happens? Is that happening while getting some nested element inside `Producer` ? — Leviand, Sep 06 '18 at 06:19
you could use Dynamic entity graphs can be the better solution, if you need to define a use case specific graph.If Join fetch is not working. — Angad Bansode, Sep 06 '18 at 06:38

Angad Bansode · Answer 1 · 2018-09-06T07:44:01.350

If join fetch is throwing LIEX then i could suggest use Dynamic Entity Graph, because if you need to define a use case specific graph.

Lets try this one, i did and work for me.

public class DynamicEntityGraphDemo {

    public static void main(String[] args) {

        EntityManager em = HibernateUtil.getEntityManager();
        EntityGraph graph = em.createEntityGraph(Product.class);
        Subgraph itemGraph = graph.addSubgraph("producerEntities");

        Map hints = new HashMap();
        hints.put("javax.persistence.loadgraph", graph);

        Product pro = em.find(Product.class, 1, hints);
        System.out.println("DynamicEntityGraphDemo pro  = " + pro.toString() + 
                 "producer =  " + pro.getProducerEntities().toString());
    }
}

NOTE : Dynamic Entity Graph uses LEFT OUTER JOIN while retrieving child entity. (Subgraph itemGraph = graph.addSubgraph("producerEntities");)

score 0 · Answer 2 · answered Sep 06 '18 at 09:48

0

join fetch p.producerEntities, not p.producer..

answered Sep 06 '18 at 09:48

Christopher

345
2
9

you're right. it is just my syntax error(query work most of the times). – M2E67 Sep 08 '18 at 06:02

score 0 · Accepted Answer · answered Jan 16 '19 at 09:05

0

Problem was from my collection setter and getter methods name. It issolved.

answered Jan 16 '19 at 09:05

M2E67

818
7
21

Could you please elaborate exactly what you had to change. – Dave Apr 27 '21 at 01:28

Tiago Medici · Answer 4 · 2021-04-27T06:14:16.953

there are many ways to solve, using hibernate properties

@Bean
public DataSource dataSource() {
    DriverManagerDataSource dataSource = new DriverManagerDataSource(); 
    return dataSource;
}

@Bean
public LocalSessionFactoryBean getSessionFactory() throws IOException {
    LocalSessionFactoryBean factoryBean = new LocalSessionFactoryBean();
    factoryBean.setDataSource(dataSource()); 

    Properties hibernateProperties = new Properties(); 
    hibernateProperties.setProperty("hibernate.enable_lazy_load_no_trans", "true"); 
    factoryBean.setHibernateProperties(hibernateProperties);
    factoryBean.afterPropertiesSet();

    return factoryBean;
}

@Bean
public HibernateTransactionManager getTransactionManager() throws IOException {
    HibernateTransactionManager transactionManager = new HibernateTransactionManager();
    transactionManager.setSessionFactory(getSessionFactory().getObject());
    return transactionManager;
}

or you can use

org.hibernate.annotations.@Proxy 

@Entity
@Table(name = "ACTOR")
@Proxy(lazy = false)
public class Actor

"hibernate.enable_lazy_load_no_trans" is considered an anti-pattern as is eager loading with n+1 queries. The whole point of FetchType.LAZY and JOIN FETCH is to address this. — Dave, Apr 27 '21 at 01:20

Hibernate Lazy Initialization exception even using Join Fetch in HQL queries

4 Answers4