How to insert new items with Hibernate?

Question

I have an entity class called Task which is mapped in hibernate.

I'm able to fetch existing items belonging to this class correctly, so I don't think this is an issue with the mapping of the class.

However, when I try to insert a new item, I get the following error:

org.hibernate.exception.SQLGrammarException: error performing isolated work
    at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:80)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112)
    at org.hibernate.engine.transaction.internal.jdbc.JdbcIsolationDelegate.delegateWork(JdbcIsolationDelegate.java:96)
    at org.hibernate.id.enhanced.TableStructure$1.getNextValue(TableStructure.java:131)
    at org.hibernate.id.enhanced.NoopOptimizer.generate(NoopOptimizer.java:58)
    at org.hibernate.id.enhanced.SequenceStyleGenerator.generate(SequenceStyleGenerator.java:422)
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:117)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:209)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:194)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:114)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
    at org.hibernate.internal.SessionImpl.fireSaveOrUpdate(SessionImpl.java:680)
    at org.hibernate.internal.SessionImpl.saveOrUpdate(SessionImpl.java:672)

In the following code:

Task t = new Task();
t.title = "foo";
t.comment = "bar";
//snip... (every single field of task is given some value, except for id)

session.saveOrUpdate("Task", t); //This is the line on which the exception occurs

If I don't do saveOrUpdate() , then the new task isn't inserted into the db.

What am I doing wrong?

Edit: session.save(task) doesn't work either

Answer 1

Got this to work with the help of this link: http://www.coderanch.com/t/487173/ORM/databases/hibernate-sequence-exist

Apparently hibernate looks for sequence tables for generating the id. Setting the following:

@GeneratedValue(strategy = GenerationType.IDENTITY)

on the id, causes it to use the underlying db's auto increment and not try to generate the id itself, and now it works.

Answer 2

If someone else is struggling with this error, I fixed it by removing

<prop key="hibernate.id.new_generator_mappings">true</prop>

From hibernate properties.

Answer 3

I accidentally removed hibernate_sequence table in my db. Change:

spring.jpa.hibernate.ddl-auto=none

to

spring.jpa.hibernate.ddl-auto=create

In your application.properties file so Hibernate could recreate this table by himself