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@Converter
public class CustomerTransformer {

    private static final Logger LOG = LoggerFactory.getLogger(CustomerTransformer.class);

    /**
     * A transformation method to convert a person document into a customer
     * entity
     */
    @Converter
    public static CustomerEntity toCustomer(PersonDocument doc, Exchange exchange) throws Exception {
        EntityManager entityManager = exchange.getIn().getHeader(JpaConstants.ENTITYMANAGER, EntityManager.class);
        TransactionTemplate transactionTemplate = exchange.getContext().getRegistry().lookupByNameAndType("transactionTemplate", TransactionTemplate.class);

        String user = doc.getUser();
        CustomerEntity customer = findCustomerByName(transactionTemplate, entityManager, user);

        // let's convert information from the document into the entity bean
        customer.setUserName(user);
        customer.setFirstName(doc.getFirstName());
        customer.setSurname(doc.getLastName());
        customer.setCity(doc.getCity());

        LOG.info("Created object customer: {}", customer);
        return customer;
    }

    /**
     * Finds a customer for the given username
     */
    private static CustomerEntity findCustomerByName(TransactionTemplate transactionTemplate, final EntityManager entityManager, final String userName) throws Exception {
        return transactionTemplate.execute(new TransactionCallback<CustomerEntity>() {
            public CustomerEntity doInTransaction(TransactionStatus status) {
                entityManager.joinTransaction();
                List<CustomerEntity> list = entityManager.createNamedQuery("findCustomerByUsername", CustomerEntity.class).setParameter("userName", userName).getResultList();
                CustomerEntity answer;
                if (list.isEmpty()) {
                    answer = new CustomerEntity();
                    answer.setUserName(userName);
                    LOG.info("Created a new CustomerEntity {} as no matching persisted entity found.", answer);
                } else {
                    answer = list.get(0);
                    LOG.info("Found a matching CustomerEntity {} having the userName {}.", answer, userName);
                }

                return answer;
            }
        });
    }

}

{snippet:id=example|lang=java|url=camel/trunk/examples/camel-example-etl/src/main/java/org/apache/camel/example/etl/CustomerTransformer.java}