Spring batch doesnt start transaction when using custom writer

Question

I am working on a spring batch which reads from a csv file and writes into database. i am using FlatFileItemReader for reading the file and implemented ItemWriter which uses Jpa to insert data into database. But batch fails with no transaction in progress. Here is my job configuration

<bean id="datasource" class="oracle.jdbc.pool.OracleDataSource">
    <property name="user" value="xxx" />
    <property name="password" value="xx" />
    <property name="URL" value="xxx" />
</bean>

<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory"/>
</bean>

<bean id="entityManagerFactory" name="model"
      class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="dataSource" ref="datasource"/>

    <property name="jpaVendorAdapter">
        <bean
                class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
            <property name="generateDdl" value="false"/>
            <property name="showSql" value="true"/>
            <property name="database">
                <util:constant
                        static-field="org.springframework.orm.jpa.vendor.Database.ORACLE"/>
            </property>
            <property name="databasePlatform" value="org.hibernate.dialect.Oracle12cDialect"/>
        </bean>
    </property>
</bean>

<batch:job id="testJob">
    <batch:step id="step">
        <batch:tasklet>
            <batch:chunk reader="cvsFileItemReader" writer="databaseWriter"
                         commit-interval="10">
            </batch:chunk>
        </batch:tasklet>
    </batch:step>
</batch:job>

And below is my writer

public class DatabaseWriter implements ItemWriter<Report> {


private EntityManagerFactory entityManagerFactory;

@Autowired
public DatabaseWriter(EntityManagerFactory entityManagerFactory) {
    this.entityManagerFactory = entityManagerFactory;
}

@Override
public void write(List<? extends Report> list) throws Exception {
    EntityManager entityManager = entityManagerFactory.createEntityManager();
    for (Report report : list) {


        entityManager.persist(report );
    }
    entityManager.flush();

}

}

It only works if start transaction explicitly .that is like below

public class DatabaseWriter implements ItemWriter<Report> {


private EntityManagerFactory entityManagerFactory;

@Autowired
public DatabaseWriter(EntityManagerFactory entityManagerFactory) {
    this.entityManagerFactory = entityManagerFactory;
}

@Override
public void write(List<? extends Report> list) throws Exception {
    EntityManager entityManager = entityManagerFactory.createEntityManager();
    entityManager.getTransaction().begin();
    for (Report report : list) {

        entityManager.persist(report );
    }
    entityManager.getTransaction().commit();

}

}

Is it really needed that transaction should be maintained explicitly and spring batch doesn't control it out of box?

EDIT

I fixed it by changing writer like

public class DatabaseWriter implements ItemWriter<Report> {


@PersistenceContext
private EntityManager entityManager;

@Override

public void write(List<? extends Report> list)  {
    for (Report report : list) {
        entityManager.persist(report );
    }


}

Changing EntityMangerFactory to EntityManager with PersistenceContext fixed the problem. But i am struggling to understand reason for this behaviour

Sushil Behera Sushil Behera · Accepted Answer · 2019-10-17T22:13:37

Create DAO and move your JPA code there and autowire the DAO in your writer.

Also make sure you autowire the entity manager like below.

@PersistenceContext
private EntityManager em;

Spring batch doesnt start transaction when using custom writer

2 Answers