my issue is very related to the following:
Why am I getting a Hibernate LazyInitializationException in this Spring MVC web application when the data displays correctly?
I have the following properties on a particular entity:
@OneToMany(fetch = FetchType.EAGER, cascade = {CascadeType.REMOVE})
@JoinColumn(referencedColumnName = "id", name = "ID_FORMAT_FILE")
private List<ColumnFormat> columnList;
@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(name = "FILEFORMAT_ORIGINATOR", joinColumns = @JoinColumn(name = "FILEFORMAT_ID", referencedColumnName = "id")
, inverseJoinColumns = @JoinColumn(name = "ORIGINATOR_ID", referencedColumnName = "id"))
private List<Originator> originators;
As you might have noticed I have an Eager Fetch type on both relations, but it is giving the following:
Caused by: org.hibernate.loader.MultipleBagFetchException: cannot simultaneously fetch multiple bags
at org.hibernate.loader.BasicLoader.postInstantiate(BasicLoader.java:94)
at org.hibernate.loader.entity.EntityLoader.<init>(EntityLoader.java:119)
at org.hibernate.loader.entity.EntityLoader.<init>(EntityLoader.java:71)
at org.hibernate.loader.entity.EntityLoader.<init>(EntityLoader.java:54)
at org.hibernate.loader.entity.BatchingEntityLoader.createBatchingEntityLoader(BatchingEntityLoader.java:133)
at org.hibernate.persister.entity.AbstractEntityPersister.createEntityLoader(AbstractEntityPersister.java:1914)
at org.hibernate.persister.entity.AbstractEntityPersister.createEntityLoader(AbstractEntityPersister.java:1937)
at org.hibernate.persister.entity.AbstractEntityPersister.createLoaders(AbstractEntityPersister.java:3205)
at org.hibernate.persister.entity.AbstractEntityPersister.postInstantiate(AbstractEntityPersister.java:3191)
at org.hibernate.persister.entity.SingleTableEntityPersister.postInstantiate(SingleTableEntityPersister.java:728)
at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:348)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1845)
at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:902)
... 33 more
I must access both lists List<ColumnFormat> columnList
and List<Originator> originators
on different beans, but if both are of Fetch Type Eager I get the above problem, and if one of them is Lazy I get the following:
Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: xxx.xxx.xxx.xxx.FileFormat.originators, no session or session was closed
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:383)
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:375)
at org.hibernate.collection.AbstractPersistentCollection.readElementExistence(AbstractPersistentCollection.java:157)
at org.hibernate.collection.PersistentBag.contains(PersistentBag.java:262)
at java.util.ArrayList.batchRemove(ArrayList.java:632)
at java.util.ArrayList.removeAll(ArrayList.java:605)
at xxx.xxx.xxx.xxx.bean.FileFormatEdit.init(FileFormatEdit.java:1040)
... 75 more
Is there a way to retrieve the lists on the different beans without having these problems?
Enum FetchType. Defines strategies for fetching data from the database. The EAGER strategy is a requirement on the persistence provider runtime that data must be eagerly fetched. The LAZY strategy is a hint to the persistence provider runtime that data should be fetched lazily when it is first accessed.
I came to notice that the default FetchType for the @ManyToOne mapping is EAGER in JPA and Hibernate, whereas for the @OneToMany mapping, the default FetchType is LAZY .
The FETCH keyword of the JOIN FETCH statement is JPA-specific. It tells the persistence provider to not only join the 2 database tables within the query but to also initialize the association on the returned entity. You can use it with a JOIN and a LEFT JOIN statement.
Haven't encountered this problem before, but just googling "cannot simultaneously fetch multiple bags" returns this link on the Hibernate forums.
One of the blog posts in that link may contain the solution you're looking for.
I deleted all fetch=FetchType.EAGER
and it work correct. I´m usign Hibernate 3.5.6-Final, Spring 3.0.4 and Junit 4. I think fetch-EAGER is by default, because my object loads all children.
This is sessionFactory:
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"
p:dataSource-ref="dataSource"
p:packagesToScan="org.pfc.modelo">
<property name="hibernateProperties">
<props>
<prop key="dialect">org.hibernate.dialect.Oracle10gDialect</prop>
<prop key="show_sql">true</prop>
<prop key="format_sql">true</prop>
</props>
</property>
</bean>
This is class:
@Entity
@Table(name="D_ACTIVIDAD")
public class Actividad implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@SequenceGenerator(sequenceName="SQ_ACTIVIDAD",name="seqActividad")
@GeneratedValue(strategy=GenerationType.SEQUENCE,generator="seqActividad")
private Integer idActividad;
@Column(name="FECHA",nullable=false)
@Temporal(TemporalType.TIMESTAMP)
private Calendar fecha;
@Column(name="TITULO",nullable=false)
private String titulo;
@Column(name="TEXTO",nullable=false)
private String texto;
@ManyToOne
@JoinColumn(name="IDASOCIACION")
private Asociacion asociacion;
@OneToMany(mappedBy="actividad",cascade=CascadeType.ALL,orphanRemoval=true)
private List<ComentarioActividad> comentarios;
@OneToMany(mappedBy="actividad",cascade=CascadeType.ALL,orphanRemoval=true)
@OrderBy(value="fecha")
private List<Documento> documentos;
//set and get methods
...........
...........
...........
}
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