Xorty Xorty - 3 months ago 70
Java Question

Spring + JPA + multiple persistence units: Injecting EntityManager

I need to use one database for queries (non-modifying) and one for commands (modifying). I am using Spring Data JPA, so I have two configuration classes:

@Configuration
@EnableJpaRepositories(value = "com.company.read",
entityManagerFactoryRef = "readingEntityManagerFactory",
transactionManagerRef = "readingTransactionManager")
@EnableTransactionManagement
public class SpringDataJpaReadingConfiguration {

@Bean(name = "readingEntityManagerFactory")
public EntityManagerFactory readingEntityManagerFactory() {
return Persistence.createEntityManagerFactory("persistence.reading");
}

@Bean(name = "readingExceptionTranslator")
public HibernateExceptionTranslator readingHibernateExceptionTranslator() {
return new HibernateExceptionTranslator();
}

@Bean(name = "readingTransactionManager")
public JpaTransactionManager readingTransactionManager() {
return new JpaTransactionManager();
}

}

@Configuration
@EnableJpaRepositories(value = "com.company.write",
entityManagerFactoryRef = "writingEntityManagerFactory",
transactionManagerRef = "writingTransactionManager")
@EnableTransactionManagement
public class SpringDataJpaWritingConfiguration {

@Bean(name = "writingEntityManagerFactory")
public EntityManagerFactory writingEntityManagerFactory() {
return Persistence.createEntityManagerFactory("persistence.writing");
}

@Bean(name = "writingExceptionTranslator")
public HibernateExceptionTranslator writingHibernateExceptionTranslator() {
return new HibernateExceptionTranslator();
}

@Bean(name = "writingTransactionManager")
public JpaTransactionManager writingTransactionManager() {
return new JpaTransactionManager();
}

}


In my repository I sometimes need to decide with EntityManager to use like so:

@Repository
public class UserReadingRepository {

@PersistenceContext(unitName = "persistence.reading")
private EntityManager em;

// some useful queries here
}


I am using persistence unit's name as defined in my persistence.xml:

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0">

<persistence-unit name="persistence.reading" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<non-jta-data-source>ReadingDS</non-jta-data-source>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
<property name="hibernate.show_sql" value="true" />
</properties>
</persistence-unit>

<persistence-unit name="persistence.writing" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<non-jta-data-source>WritingDS</non-jta-data-source>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
<property name="hibernate.show_sql" value="true" />
</properties>
</persistence-unit>

</persistence>


Spring throws
org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'persistence.reading'
is defined. Oddly, it looks like Spring tries to instantiate a bean with persistence unit name? Did I misconfigure something?

UPDATE: When I remove
unitName = "persistence.reading"
from @PersistenceContext annotation, I will get following error instead:
org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [javax.persistence.EntityManagerFactory] is defined: expected single matching bean but found 2: readingEntityManagerFactory,writingEntityManagerFactory


UPDATE 2: Rohit suggested (in the comment) to wire
EntityManagerFactory
instead. So I tried to do the following:

@PersistenceUnit(unitName = "persistence.reading")
private EntityManagerFactory emf;


but Spring only reports:
org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'persistence.reading' is defined


FINAL FIX:
Thanks to Vlad's answer, I was able to update the code to use the following (just make sure you define your
dataSource
bean as well):

@Bean(name = "readingEntityManagerFactory")
public EntityManagerFactory readingEntityManagerFactory() {
LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
em.setPersistenceUnitName("persistence.reading");
em.setDataSource(dataSource());
em.setPackagesToScan("com.company");
em.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
em.afterPropertiesSet();
return em.getObject();
}

Answer

The EntityManageFactory is not properly configured. You should use a LocalContainerEntityManagerFactoryBean instead:

@Bean(name = "readingEntityManagerFactory")
public EntityManagerFactory readingEntityManagerFactory() {
    LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
    em.setPersistenceUnitName("persistence.reading");
    em.setDataSource(dataSource());
    em.setPackagesToScan("com.company");
    em.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
    em.afterPropertiesSet();
    return em.getObject();
}

Also the JpaTransactionManager is miss-configured too. It should be something like:

@Bean(name = "readingTransactionManager")
public PlatformTransactionManager readingTransactionManager(){
    JpaTransactionManager transactionManager = new JpaTransactionManager();
    transactionManager.setEntityManagerFactory(readingEntityManagerFactory());
    return transactionManager;
}

You need to do the same for both the reading and the writing EntityManager configurations.

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