ImprovedNamingStrategy no longer working in Hibernate 5

Question

I have simple spring-jpa configuration where I have configured Hibernate's ImprovedNamingStrategy. This means if my entity class has a variable userName, then Hibernate should convert it to user_name for querying the database. But this naming conversion stopped working after I upgraded to Hibernate 5. I am getting the error:

ERROR: Unknown column 'user0_.userName' in 'field list'

This is my Hibernate config:

@Configuration
@EnableJpaRepositories("com.springJpa.repository")
@EnableTransactionManagement
public class DataConfig {

    @Bean
    public DataSource dataSource(){
        DriverManagerDataSource ds = new DriverManagerDataSource();
        ds.setDriverClassName("com.mysql.jdbc.Driver");
        ds.setUrl("jdbc:mysql://localhost:3306/test");
        ds.setUsername("root");
        ds.setPassword("admin");
        return ds;
    }


    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(){ 

        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        vendorAdapter.setShowSql(Boolean.TRUE);
        vendorAdapter.setDatabase(Database.MYSQL);

        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setJpaVendorAdapter(vendorAdapter);
        factory.setDataSource(dataSource());
        factory.setPackagesToScan("com.springJpa.entity");


        Properties jpaProperties = new Properties();

        jpaProperties.put("hibernate.ejb.naming_strategy","org.hibernate.cfg.ImprovedNamingStrategy");
        jpaProperties.put("hibernate.dialect","org.hibernate.dialect.MySQL5InnoDBDialect");

        factory.setJpaProperties(jpaProperties);
        factory.afterPropertiesSet();
        return factory;
    }

    @Bean
    public SharedEntityManagerBean entityManager() {
        SharedEntityManagerBean entityManager = new SharedEntityManagerBean();
        entityManager.setEntityManagerFactory(entityManagerFactory().getObject());
        return entityManager;
    }



    @Bean
    public PlatformTransactionManager transactionManager() {
        JpaTransactionManager txManager = new JpaTransactionManager();
        txManager.setEntityManagerFactory(entityManagerFactory().getObject());
        return txManager;
    }

    @Bean
    public ImprovedNamingStrategy namingStrategy(){
        return new ImprovedNamingStrategy();
    }
}

This is my Entity class:

@Getter
@Setter
@Entity
@Table(name="user")
public class User{

    @Id
    @GeneratedValue
    private Long id;

    private String userName;
    private String email;
    private String password;
    private String role;

}

I don't want to explicitly name my database fields within the @Column annotations. I want my configuration which can implicitly convert camel case to underscore.

Please guide.

Answer 1

Thanks for posting your own solution. It helps me so much to set Hibernate 5 naming strategy!

The hibernate.ejb.naming_strategy property of pre-Hibernate 5.0 seems split into two parts:

• hibernate.physical_naming_strategy
• hibernate.implicit_naming_strategy

The values of these properties do not implement the NamingStrategy interface as did hibernate.ejb.naming_strategy. There are two new interfaces for these purposes:

• org.hibernate.boot.model.naming.PhysicalNamingStrategy
• org.hibernate.boot.model.naming.ImplicitNamingStrategy

Hibernate 5 provides only one implementation of PhysicalNamingStrategy (PhysicalNamingStrategyStandardImpl) that assumes physical identifier names are the same as logical ones.

There are several implementations of ImplicitNamingStrategy but I found none equivalent to the old ImprovedNamingStrategy. (See: org.hibernate.boot.model.naming.ImplicitNamingStrategyLegacyHbmImpl)

So, I implemented my own PhysicalNamingStrategy which is very simple:

public class PhysicalNamingStrategyImpl extends PhysicalNamingStrategyStandardImpl implements Serializable {

 public static final PhysicalNamingStrategyImpl INSTANCE = new PhysicalNamingStrategyImpl();

 @Override
 public Identifier toPhysicalTableName(Identifier name, JdbcEnvironment context) {
     return new Identifier(addUnderscores(name.getText()), name.isQuoted());
 }

 @Override
 public Identifier toPhysicalColumnName(Identifier name, JdbcEnvironment context) {
     return new Identifier(addUnderscores(name.getText()), name.isQuoted());
 }


 protected static String addUnderscores(String name) {
     final StringBuilder buf = new StringBuilder( name.replace('.', '_') );
     for (int i=1; i<buf.length()-1; i++) {
        if (
             Character.isLowerCase( buf.charAt(i-1) ) &&
             Character.isUpperCase( buf.charAt(i) ) &&
             Character.isLowerCase( buf.charAt(i+1) )
         ) {
             buf.insert(i++, '_');
         }
     }
     return buf.toString().toLowerCase(Locale.ROOT);
 }
}

Note that the addUnderscores() method is from the original org.hibernate.cfg.ImprovedNamingStrategy.

Then, I set this physical strategy into the persistence.xml file :

  <property name="hibernate.physical_naming_strategy" value="my.package.PhysicalNamingStrategyImpl" />

It is a trap to set Hibernate 5 naming strategy as previous version settings.