JPA Inheritance with JOINED strategy

Question

I've seen many posts about inheritance but nothing match my problem.

I try to build a correct objects model:

The root class

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
public abstract class Identity {

    @Id
    @GeneratedValue
    public long id;

}

An intermediate class

@Entity
public class Group extends Identity {

    @ManyToMany
    public Collection<Identity> identities = new HashSet<>();

}

Two other class, one that inherits from Group and the other from Identity

@Entity
public class Abonne extends Group {}

@Entity
public class User extends Identity {}

I use springboot 1.5.2 and a mysql database. I allready have some application with the same configuration, but it's the first time I try such an inheritance model.

When I run springboot, it launches exceptions at tables creation time:

org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:1.5.2.RELEASE:run (default-cli) on project mova.pcp: An exception occurred while running. null
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:212)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
    at org.codehaus.classworlds.Launcher.main(Launcher.java:47)
Caused by: org.apache.maven.plugin.MojoExecutionException: An exception occurred while running. null
    at org.springframework.boot.maven.AbstractRunMojo$IsolatedThreadGroup.rethrowUncaughtException(AbstractRunMojo.java:495)
    at org.springframework.boot.maven.RunMojo.runWithMavenJvm(RunMojo.java:95)
    at org.springframework.boot.maven.AbstractRunMojo.run(AbstractRunMojo.java:249)
    at org.springframework.boot.maven.AbstractRunMojo.execute(AbstractRunMojo.java:181)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:207)
    ... 21 more
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.springframework.boot.maven.AbstractRunMojo$LaunchRunner.run(AbstractRunMojo.java:527)
    at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1081)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:856)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:314)
    at org.springframework.boot.builder.SpringApplicationBuilder.run(SpringApplicationBuilder.java:134)
    at alfresco.less.Config.main(Config.java:16)
    ... 6 more
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.persistenceException(EntityManagerFactoryBuilderImpl.java:954)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:882)
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:60)
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:353)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:370)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:359)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1687)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1624)
    ... 21 more
Caused by: org.hibernate.tool.schema.spi.SchemaManagementException: Unable to execute schema management to JDBC target [create table group (id bigint not null, primary key (id))]
    at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:59)
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlString(SchemaMigratorImpl.java:431)
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlStrings(SchemaMigratorImpl.java:420)
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.createTable(SchemaMigratorImpl.java:236)
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigrationToTargets(SchemaMigratorImpl.java:167)
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigration(SchemaMigratorImpl.java:60)
    at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:134)
    at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:101)
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:472)
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:444)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:879)
    ... 27 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'group (id bigint not null, primary key (id))' at line 1
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
    at com.mysql.jdbc.Util.getInstance(Util.java:408)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:943)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2527)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2497)
    at com.mysql.jdbc.StatementImpl.executeUpdateInternal(StatementImpl.java:1540)
    at com.mysql.jdbc.StatementImpl.executeLargeUpdate(StatementImpl.java:2595)
    at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1468)
    at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:56)
    ... 37 more

In my database I only see abonne table. I tried without abonne entity (without Entity annotation AND without extends Group) and it still not working. Then it seems that the problem comes from InheritanceType.JOINED. When I start with default inheritance strategy, it works well! But i don't want abonne data in the root table.

Any help?

Answer 1

The exception message is clear enough

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'group (id bigint

Your class is called "Group" meaning that the default name for its table is "GROUP". This is a reserved SQL keyword. As a result this name would need "quoting" (surrounding with quote marks) otherwise it would be illegal.

Some JPA providers (e.g DataNucleus, any others?) auto-quote this for you, but seemingly yours does not. Your solution is to either add quotes to the table name via an @Table(name=...)!, or rename the class!, or use a JPA provider that auto quotes it for you.

i.e nothing at all to do with the inheritance chosen (except that with "SINGLE_TABLE" inheritance it has no need to create a table that uses a reserved keyword).

Answer 2

You should not name a table Group because Group is a reserved SQL keyword.

Either rename the class or add a @Table annotation to provide a different table name.