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I am using Hibernate with spring.
I have a model-class like this.
@Entity
@Table(name = "forumtopic")
public final class Forumtopic extends AbstractUserTracking implements
java.io.Serializable {
/**SNIP **/
private Forumcategory forumcategory;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "FkForumcategoryId", nullable = false)
public Forumcategory getForumcategory() {
return this.forumcategory;
}
public void setForumcategory(final Forumcategory forumcategory) {
this.forumcategory = forumcategory;
}
}
It works in general, but the Category is not loaded lazy, but eagerly after the ForumEntry has been loaded.
Hibernate:
select
forumtopic0_.PkId as PkId19_0_,
forumtopic0_.CreateDate as CreateDate19_0_,
forumtopic0_.FkCreateUserId as FkCreate3_19_0_,
forumtopic0_.FkLastUserId as FkLastUs4_19_0_,
forumtopic0_.LastChange as LastChange19_0_,
forumtopic0_.FkForumcategoryId as FkForum10_19_0_,
forumtopic0_.PublishCategory as PublishC6_19_0_,
forumtopic0_.State as State19_0_,
forumtopic0_.Text as Text19_0_,
forumtopic0_.Topic as Topic19_0_,
forumtopic0_.FkTpUserId as FkTpUserId19_0_
from
forumtopic forumtopic0_
where
forumtopic0_.PkId=?
Hibernate:
select
forumcateg0_.PkId as PkId17_0_,
forumcateg0_.CreateDate as CreateDate17_0_,
forumcateg0_.Name as Name17_0_,
forumcateg0_.FkRequestId as FkReques4_17_0_,
forumcateg0_.FkTpUserId as FkTpUserId17_0_
from
forumcategory forumcateg0_
where
forumcateg0_.PkId=?
Altough the getter was not called the ForumCategory is loaded right after ForumTopic.
This problems appears in all my @ManyToOne-associations. However @OneToMany associating are loaded lazily.
I am using maven2 for the build. These are my dependencies.
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring</artifactId>
<version>2.5.6</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>3.3.1.GA</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>ejb3-persistence</artifactId>
<version>1.0.2.GA</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-annotations</artifactId>
<type>jar</type>
<version>3.4.0.GA</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<type>jar</type>
<version>3.4.0.GA</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-search</artifactId>
<version>3.1.0.GA</version>
</dependency>
Can someone please help me understand what is happening?
594
The FetchType. LAZY tells Hibernate to only fetch the related entities from the database when you use the relationship. This is a good idea in general because there's no reason to select entities you don't need for your uses case. You can see an example of a lazily fetched relationship in the following code snippets.
To enable lazy loading explicitly you must use “fetch = FetchType. LAZY” on an association that you want to lazy load when you are using hibernate annotations. @OneToMany( mappedBy = "category", fetch = FetchType.
LAZY or FetchType. EAGER . By default, @OneToMany and @ManyToMany associations use the FetchType. LAZY strategy while the @OneToOne and @ManyToOne use the FetchType.
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 guess it's caused by the fact that your classes are declared as final, therefore Hibernate cannot generate lazy proxies for them. Try to remove final from class declarations.
122
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