Why am I getting a Primary Key violation for an @OneToMany property?

Question

I have an entity:

@Entity
public class Student {

    @GeneratedValue(strategy = GenerationType.AUTO)
    @Id
    private long id;

    @OneToMany
    private Set<Course> courses;
}

When I try to persist the first entity of this type it works fine, but then when I try to save a new Student with the same course as the already stored entity it fails. Here is the error:

insert into student_courses (student, courses) values (?, ?) [23505-172]]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement] with root cause

org.h2.jdbc.JdbcSQLException: Unique index or primary key violation: "UK_1DBE7B943AC44E1B841DA2688EB_INDEX_5 ON PUBLIC.STUDENT_COURSES(COURSES)"; SQL statement:
insert into student_courses (student, courses) values (?, ?) [23505-172]
    at org.h2.message.DbException.getJdbcSQLException(DbException.java:329)
    at org.h2.message.DbException.get(DbException.java:169)
    at org.h2.message.DbException.get(DbException.java:146)
    at org.h2.index.BaseIndex.getDuplicateKeyException(BaseIndex.java:83)
    at org.h2.index.TreeIndex.add(TreeIndex.java:65)
    at org.h2.table.RegularTable.addRow(RegularTable.java:124)
    at org.h2.command.dml.Insert.insertRows(Insert.java:126)
    at org.h2.command.dml.Insert.update(Insert.java:86)
    at org.h2.command.CommandContainer.update(CommandContainer.java:79)
    at org.h2.command.Command.executeUpdate(Command.java:235)
    at org.h2.jdbc.JdbcPreparedStatement.executeUpdateInternal(JdbcPreparedStatement.java:154)
    at org.h2.jdbc.JdbcPreparedStatement.executeUpdate(JdbcPreparedStatement.java:140)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:133)
    at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:58)
    at org.hibernate.persister.collection.AbstractCollectionPersister.recreate(AbstractCollectionPersister.java:1256)
    at org.hibernate.action.internal.CollectionRecreateAction.execute(CollectionRecreateAction.java:58)
    at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:364)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:356)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:281)
    at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:328)
    at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:52)
    at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1234)
    at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:404)
    at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101)
    at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:175)
    at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:75)
    at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:515)
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:757)
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:726)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:478)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:272)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:158)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.jpa.repository.support.LockModeRepositoryPostProcessor$LockModePopulatingMethodIntercceptor.invoke(LockModeRepositoryPostProcessor.java:92)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207)
    at com.sun.proxy.$Proxy45.save(Unknown Source)
    at students.StudentController.createRandomShiur(ShiurimController.java:66)
    at shiurim.StudentController.getStudents(StudentController.java:26)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:220)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:746)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:687)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:946)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:822)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.valves.RemoteIpValve.invoke(RemoteIpValve.java:680)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1686)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
    at java.lang.Thread.run(Thread.java:695)

I am using Spring Data JPA with Hibernate and H2 as the database.

The application created its own database tables:

HibernateJpaVendorAdapter hibernateJpaVendorAdapter = new HibernateJpaVendorAdapter();
hibernateJpaVendorAdapter.setShowSql(false);
hibernateJpaVendorAdapter.setGenerateDdl(true);
hibernateJpaVendorAdapter.setDatabase(Database.H2);

So, why would there be a unique constraint?

Update:

I see that Hibernate added the constraint:

Hibernate: alter table student_courses add constraint UK_a8c48f36df374f1293c46699c83 unique (courses)

How do I tell Hibernate not to create that?

Thanks!

score 16 · Accepted Answer · answered Dec 27 '13 at 17:56

16

Since the violation happens in the STUDENT_COURSES table, it seems like you are trying to persist the same relationship twice. You mapped a Set, which signals Hibernate that these relationships must occur not more than once. Check the generated DDL for unique indexes on COURSE_ID, STUDENT_ID).

The reason may be a flaw in your program logic (eg. modifying fields relevant to equals on Courses after they are added to the set or a faulty equals in your Course entity.

You have to decide yourself (your client in the real world, since this is a business decision), if a Student can participate in a Course more than once (e.g. failed the first time).

answered Dec 27 '13 at 17:56

atamanroman

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This is trying to insert two students with the same course. The students are unique. The courses are the same. Why would Hibernate create a unique index there? – Adam Dec 27 '13 at 18:00
5

Please show your `Courses` entity. Looks like your mapping is wrong. Maybe it's `@ManyToMany` or you're missing a `mappedBy` on the weak side, if the mapping is on both sides. – atamanroman Dec 27 '13 at 20:18
3

Yes, you're right, I should be using `@ManyToMany`. I was only thinking about a student taking multiple courses when I wrote the entity, but since multiple students can take the same course it is really `@ManyToMany`, that fixed it, thanks! – Adam Dec 27 '13 at 21:35

bNd · Answer 2 · 2013-12-28T06:03:58.613

1

You have to use GenerationType.TABLE instead of GenerationType.AUTO. That way, jpa uses a sequence table for id assignment and you may never need to generate sequence or auto-increment values or triggers that lowers portability.

edited Dec 28 '13 at 06:03

answered Dec 27 '13 at 17:42

bNd

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That did not work. I changed to GenerationType.TABLE instead of AUTO for the ID of both the student and the course. I still get the same error. – Adam Dec 27 '13 at 17:49

score 0 · Answer 3 · answered Mar 24 '20 at 09:43

The is likely that you set @OneToMany while you actually have a @ManyToMany relationship.

Assuming that Course has no autogenerated Id, then there will be a problem as soon as the second student will add a Course with the same name.
Since it is a one to many relationship a new course will be created with the same unique restricted Id

score -1 · Answer 4 · answered Dec 27 '13 at 17:55

-1

It is not the problem with Sequence / JPA /hibern.As per your log the error happend on student_courses

insert into student_courses 

UK_1DBE7B943AC44E1B841DA2688EB_INDEX_5

Seems , you have unquie constraint in student_course table with courses. remove that unquie constraint / you may need to add composite of student and courses for unquie constraint not just courses.

answered Dec 27 '13 at 17:55

Mani

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The constraints and the tables are all generated by the application itself {{hibernateJpaVendorAdapter.setGenerateDdl(true)}}, so the question becomes why did Hibernate create that constraint? – Adam Dec 27 '13 at 18:01
1

Since your courses is Set, it assumed to have unquie. you can use @CollectionTable annotation to avoid this .. Check the http://stackoverflow.com/questions/13123076/unique-constraint-for-setstring-with-hibernate – Mani Dec 27 '13 at 18:12

Why am I getting a Primary Key violation for an @OneToMany property?

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