Can't set JPA naming strategy after configuring multiple data sources (Spring 1.4.1 / Hibernate 5.x)

I am using Spring Boot 1.4.1 which uses Hibernate 5.0.11. Initially I configured a data source using application.properties like this:

spring.datasource.uncle.url=jdbc:jtds:sqlserver://hostname:port/db
spring.datasource.uncle.username=user
spring.datasource.uncle.password=password
spring.datasource.uncle.dialect=org.hibernate.dialect.SQLServer2012Dialect
spring.datasource.uncle.driverClassName=net.sourceforge.jtds.jdbc.Driver

I configured it with "uncle" because that will be the name of one of multiple data sources that I'll configure. I configured this data source like this, according to the Spring docs:

@Bean
@Primary
@ConfigurationProperties(prefix = "spring.datasource.uncle")
public DataSource uncleDataSource() {
	return DataSourceBuilder.create().build();
}

At this point everything worked fine.

I created an @Entity class without any @Column annotations and let Hibernate figure out the column names, for example if I have a Java property named idBank, Hibernate will automatically assume the column name is id_bank. This is used when generating ddl, running SQL statements, etc. I want to utilize this feature because I'm going to have a lot of entity classes and don't want to have to create and maintain all of the @Column annotations. At this point, this worked fine.

I then added another data source like this:

spring.datasource.aunt.url=jdbc:sybase:Tds:host2:port/db2
spring.datasource.aunt.username=user2
spring.datasource.aunt.password=password2
spring.datasource.aunt.dialect=org.hibernate.dialect.SybaseDialect
spring.datasource.aunt.driverClassName=com.sybase.jdbc4.jdbc.SybDriver

... and also this, following the Spring docs for setting up multiple data sources. Apparently once you define a 2nd data source, it can't configure the default beans and you have to define your own EntityManager and TransactionManager. So in addition to the data source configured above, I added these configurations:

@Bean
@Primary
PlatformTransactionManager uncleTransactionManager(@Qualifier("uncleEntityManagerFactory") final EntityManagerFactory factory) {
	return new JpaTransactionManager(factory);
}

@Bean
@Primary
LocalContainerEntityManagerFactoryBean uncleEntityManagerFactory(
        EntityManagerFactoryBuilder builder) {
    return builder
            .dataSource(uncleDataSource())
            .packages(Uncle.class)
            .persistenceUnit("uncle")
            .build();
}

@Bean
@ConfigurationProperties(prefix = "spring.datasource.aunt")
public DataSource auntDataSource() {
    return DataSourceBuilder.create().build();
}

@Bean
PlatformTransactionManager auntTransactionManager(@Qualifier("auntEntityManagerFactory") final EntityManagerFactory factory) {
    return new JpaTransactionManager(factory);
}

@Bean
LocalContainerEntityManagerFactoryBean auntEntityManagerFactory(
        EntityManagerFactoryBuilder builder) {
    return builder
            .dataSource(auntDataSource())
            .packages(Aunt.class)
            .persistenceUnit("aunt")
            .build();
}

This works in terms of connecting to the database and trying to fetch data.

HOWEVER (and here's the problem, thanks for reading this far). After these configurations I have lost the implied naming strategy that translates Java column names to snake case names, so now if I have a Java property idBank it incorrectly uses column name idBank instead of id_bank. I would really like to get that functionality back.

There is a JPA property for this spring.jpa.hibernate.naming-strategy, and there are various naming strategy classes in Spring and Hibernate such as org.springframework.boot.orm.jpa.hibernate.SpringNamingStrategy. So I tried setting it like this:

spring.jpa.hibernate.naming_strategy=org.springframework.boot.orm.jpa.hibernate.SpringNamingStrategy

But it did not work. I tried some variations such as:

spring.datasource.uncle.naming_strategy=org.springframework.boot.orm.jpa.hibernate.SpringNamingStrategy

and

spring.datasource.uncle.hibernate.naming_strategy=org.springframework.boot.orm.jpa.hibernate.SpringNamingStrategy

but this did not have any effect.

Then I read that in Hibernate 5, the naming strategy was broken up into two parts, "physical" and "implicit" and there are different settings for each. So I tried this, with a few variations:

spring.jpa.hibernate.naming.physical-strategy=org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy

and

spring.jpa.hibernate.naming.implicit-strategy=org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy

and

spring.datasource.uncle.naming.physical-strategy=org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy

and

spring.datasource.uncle.hibernate.naming.implicit-strategy=org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy

But none of these worked.

It seems like there should be a way for me to set this configuration in the beans directly, such as on the SessionFactory, but I could not find that API. The documentation around this seems to have some gaps.

I'd really like to avoid setting up a persistence.xml also, which I have not needed up to this point.

So here is where I'm stuck and I'm hoping someone can help out. Really what I would like is a way to debug these property settings, I turned on trace logging in both org.springframework and org.hibernate but there was nothing useful there. I tried stepping through the code when these beans were configured but couldn't find the place where this happens. If anyone has that info and could share it I'd be really grateful.

I had the same problem and fixed it with the following code (adapted to the code in the question - for a single entity manager):

protected Map<String, Object> jpaProperties() {
    Map<String, Object> props = new HashMap<>();
    props.put("hibernate.physical_naming_strategy", SpringPhysicalNamingStrategy.class.getName());
    props.put("hibernate.implicit_naming_strategy", SpringImplicitNamingStrategy.class.getName());
    return props;
}

@Primary
@Bean(name = "defaultEntityManager")
public LocalContainerEntityManagerFactoryBean defaultEntityManagerFactory(
    EntityManagerFactoryBuilder builder) {
    return builder
        .dataSource(auntDataSource())
        .packages(Aunt.class)
        .persistenceUnit("aunt")
        .properties(jpaProperties())
        .build();
}

The same as @ewert answer can be gained using properties:

# this works
spring.jpa.properties.hibernate.implicit_naming_strategy=org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy
spring.jpa.properties.hibernate.physical_naming_strategy=org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy

# but that doesn't work
spring.jpa.hibernate.naming.physical-strategy=org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy
spring.jpa.hibernate.naming.implicit-strategy=org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy

I think I can explain why the default behaviour disappears, as per your latest question.

As of Spring Boot 2.4.2 the deafult configuration kicks in in this method of JpaBaseConfiguration:

	@Bean
	@Primary
	@ConditionalOnMissingBean({ LocalContainerEntityManagerFactoryBean.class, EntityManagerFactory.class })
	public LocalContainerEntityManagerFactoryBean entityManagerFactory(EntityManagerFactoryBuilder factoryBuilder) {
		Map<String, Object> vendorProperties = getVendorProperties();
		customizeVendorProperties(vendorProperties);
		return factoryBuilder.dataSource(this.dataSource).packages(getPackagesToScan()).properties(vendorProperties)
				.mappingResources(getMappingResources()).jta(isJta()).build();
	}

it happens within the customizeVendorProperties method call.

By creating your own LocalContainerEntityManagerFactoryBean bean (two of them actually) this customization is not performed anymore.

If you are using SessionFactory you should use next lines to set naming strategies.

sessionFactory.setImplicitNamingStrategy(SpringImplicitNamingStrategy.INSTANCE);
sessionFactory.setPhysicalNamingStrategy(new SpringPhysicalNamingStrategy());

The only way I get this running properly with Spring-Boot 2+ was setting the following manually:

  @Bean(name = "myEmf")
  public LocalContainerEntityManagerFactoryBean sapEntityManagerFactory(
      EntityManagerFactoryBuilder builder, @Qualifier("myDataSource") DataSource dataSource) {
    return builder
        .dataSource(dataSource)
        .packages("my.custom.package")
        .persistenceUnit("myPu")
        .properties(getProperties())
        .build();
  }

  public Map<String, String> getProperties() {
   val props = new HashMap<String, String>();

    if (isTest()) {
      props.put("hibernate.hbm2ddl.auto", "create");
    } else {
      props.put("hibernate.dialect", "org.hibernate.dialect.PostgreSQL95Dialect");
    }
    return props;
  }