org.hibernate.AnnotationException: @OneToOne or @ManyToOne on entities.Ques#tion.examId references an unknown entity: long
Solution 1
If you look closely at your stacktrace, you will see
Caused by: org.hibernate.AnnotationException: @OneToOne or @ManyToOne on entities.Question.examId references an unknown entity: long
So this field
@ManyToOne
private long examId;
is causing the problem. @ManyToOne
has a paramater targetEntity
which says:
(Optional) The entity class that is the target of the association. Defaults to the type of the field or property that stores the association.
Since you haven't provided that parameter, it defaults to long
, which is not a managed Entity
.
You'll probably want to use
@ManyToOne(targetEntity = Exam.class)
private long examId;
otherwise it won't know what to map to. Or even better
@ManyToOne
private Exam exam;
Solution 2
Just add the class Team to the "hibernate-cfg.xml" file, because Hibernate doesn't identify without adding into it.
Solution 3
FYI, this sometimes happens if you have a hibernate annotation:
@org.hibernate.annotations.Entity
and a JPA annotation:
@javax.persistence.Entity
mixed up
Edit:
Explicitly import the javax annotation.
Solution 4
It took me hours to find the actual issue
I had forgotten the @Entity annotation on the Parent class and the error use to show on the child class.
Vinay Bangalore Nagaraj
Updated on July 09, 2022Comments
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Vinay Bangalore Nagaraj almost 2 years
I'm trying to setup JPA with a hibernate implementation for the first time with this test project. Ran into the following error:
Exception in thread "main" javax.persistence.PersistenceException: [PersistenceUnit: ExamModulePu] Unable to build EntityManagerFactory at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:924) at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:899) at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:59) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:63) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:47) at service.tests.ExamServiceTest.main(ExamServiceTest.java:18) Caused by: org.hibernate.AnnotationException: @OneToOne or @ManyToOne on entities.Question.examId references an unknown entity: long at org.hibernate.cfg.ToOneFkSecondPass.doSecondPass(ToOneFkSecondPass.java:109) at org.hibernate.cfg.Configuration.processEndOfQueue(Configuration.java:1536) at org.hibernate.cfg.Configuration.processFkSecondPassInOrder(Configuration.java:1457) at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1365) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1756) at org.hibernate.ejb.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:96) at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:914)
These are my entities:
@Entity public class Exam implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private long id; private String name; private int numQuestions; private int minutesAllotted; private Date startDate; private Date endDate; @OneToMany(mappedBy = "examId", orphanRemoval = true) private List<Question> questionList; // Getters and setters here.. } @Entity public class Question implements Serializable{ @Id @GeneratedValue(strategy=GenerationType.AUTO) private long id; @ManyToOne private long examId; private int points; private int timeLimit; private String text; private String category; @Embedded private List<Answer> answerList; } @Embeddable public class Answer implements Serializable { private int optionNumber; private String text; private boolean correct; }
This is what my persistence.xml looks like:
<?xml version="1.0" encoding="UTF-8"?> <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd" version="2.0"> <persistence-unit name="ExamModulePu" transaction-type="RESOURCE_LOCAL"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <class>entities.Exam</class> <class>entities.Question</class> <exclude-unlisted-classes>false</exclude-unlisted-classes> <properties> <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" /> <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/exammoduledb" /> <property name="javax.persistence.jdbc.user" value="root" /> <property name="javax.persistence.jdbc.password" value="root" /> <property name="hibernate.hbm2ddl.auto" value="create" /> </properties> </persistence-unit> </persistence>
I haven't created any of the tables, but instead am depending on the
hibernate.hb2mddl.auto
to do so. But I believe my error springs up even before that happens as it can't generate the persistence unit. Any ideas what I'm doing wrong? I'm making sure I import onlyjavax.persistence.*;
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sisimh almost 9 yearswhat is ur suggestion @CoffeJunky ?
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Monkey Supersonic about 7 yearsHis suggestion is to exclusively import
javax.persistence.Entity
instead oforg.hibernate.annotations.Entity
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Avdhut over 6 yearsThis is not the in case of my program but still giving error
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CoffeJunky over 6 yearsIs it the exact same error message? Could you share your source code?
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akasha almost 5 yearsOr in persistance.xml.