Hibernate ManyToOne with FetchType.LAZY not fetching lazy
Solution 1
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.
Solution 2
Looks like the transaction/session is closed after returning ForumTopic. Hence it becomes detached entity. When you try to do a getForumCategory there is no session to do the operation. You can prefetch the ForumCategory in the same session like,
In your getForumTopic, before returning a list (assuming you have a getAllForumTopic)
public List<ForumTopic> getAllForumTopic() {
<snip>
List<ForumTopic> topics = <SNIP: get the list of ForumTopic>
for(ForumTopic topic: topics)
topic.getForumCategory()
return topics;
}
This will fetch the ForumCategory in the same session. Otherwise you have to create a transaction in the calling function of getAllForumTopic and use the same transaction where ever you need to call getForumCategory.
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KarlsFriend
Updated on October 13, 2020Comments
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KarlsFriend over 3 years
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?
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KarlsFriend about 13 yearsThank you Sir, for sharing your wisdom.