How to inject multiple JPA EntityManager (persistence units) when using Spring

Question

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 1

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.