Persist list of Entities with <int-jpa:outbound-channel-adapter

Question

I may be missing something here but I cannot seem to find any docs about persisting a List of Entities using Spring Integration JPA Outbound Channel Adapter. I have an extremely simple scenario that should poll a database and copy new data across to another database. Thus:

<int-jpa:inbound-channel-adapter channel="myChannel"
    entity-class="my.package.MyClass"
    entity-manager="mysqlEntityManager"
    auto-startup="true">
    <int:poller fixed-rate="5000">
        <int:transactional propagation="REQUIRED" transaction-manager="mysqlTransactionManager"/>
    </int:poller>
</int-jpa:inbound-channel-adapter>

<int:channel id="myChannel" />

<int-jpa:outbound-channel-adapter channel="myChannel" 
    entity-class="my.package.MyClass"
    entity-manager="hsqldbEntityManager">
    <int-jpa:transactional transaction-manager="hsqldbTransactionManager" />                                    
</int-jpa:outbound-channel-adapter>

The inbound-channel-adapter returns a List<MyClass> and then the outbound-channel-adapter throws the stack trace below...

How do I configure the adapter to accept a list of entites? I do not want to set max messages per poll in the inbound adapter/poller, as I would prefer minimal database operations.

Any help appreciated.

Spring docs: http://static.springsource.org/spring-integration/docs/3.0.0.M1/reference/html/jpa.html

[task-scheduler-1] ERROR org.springframework.integration.handler.LoggingHandler - org.springframework.integration.MessageHandlingException: error occurred in message handler [org.springframework.integration.jpa.outbound.JpaOutboundGateway@165d2be]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:79)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:319)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
    at $Proxy24.handleMessage(Unknown Source)
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:115)
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:102)
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:77)
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:157)
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:128)
    at org.springframework.integration.core.MessagingTemplate.doSend(MessagingTemplate.java:288)
    at org.springframework.integration.core.MessagingTemplate.send(MessagingTemplate.java:149)
    at org.springframework.integration.endpoint.SourcePollingChannelAdapter.handleMessage(SourcePollingChannelAdapter.java:97)
    at org.springframework.integration.endpoint.AbstractTransactionSynchronizingPollingEndpoint.doPoll(AbstractTransactionSynchronizingPollingEndpoint.java:82)
    at org.springframework.integration.endpoint.AbstractPollingEndpoint$1.call(AbstractPollingEndpoint.java:146)
    at org.springframework.integration.endpoint.AbstractPollingEndpoint$1.call(AbstractPollingEndpoint.java:144)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:319)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
    at $Proxy23.call(Unknown Source)
    at org.springframework.integration.endpoint.AbstractPollingEndpoint$Poller$1.run(AbstractPollingEndpoint.java:236)
    at org.springframework.integration.util.ErrorHandlingTaskExecutor$1.run(ErrorHandlingTaskExecutor.java:52)
    at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:48)
    at org.springframework.integration.util.ErrorHandlingTaskExecutor.execute(ErrorHandlingTaskExecutor.java:49)
    at org.springframework.integration.endpoint.AbstractPollingEndpoint$Poller.run(AbstractPollingEndpoint.java:231)
    at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:53)
    at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:81)
    at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(Unknown Source)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalArgumentException: Unknown entity: java.util.ArrayList
    at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:692)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:240)
    at $Proxy18.merge(Unknown Source)
    at org.springframework.integration.jpa.core.DefaultJpaOperations.merge(DefaultJpaOperations.java:175)
    at org.springframework.integration.jpa.core.JpaExecutor.executeOutboundJpaOperation(JpaExecutor.java:223)
    at org.springframework.integration.jpa.outbound.JpaOutboundGateway.handleRequestMessage(JpaOutboundGateway.java:81)
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:134)
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:73)
    ... 48 more
Caused by: org.hibernate.MappingException: Unknown entity: java.util.ArrayList
    at org.hibernate.impl.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:693)
    at org.hibernate.impl.SessionImpl.getEntityPersister(SessionImpl.java:1485)
    at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:232)
    at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:84)
    at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:867)
    at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:851)
    at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:855)
    at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:686)
    ... 59 more

Answer 1

I have created a Jira in order to make that improvement:

https://jira.springsource.org/browse/INT-3029

As a work-around you could also extend DefaultJpaOperations (org.springframework.integration.jpa.core) and customize the persist() method, allowing you to handle a Collection type parameters. For some details see:

Batch inserts with JPA/EJB3

The adapters have an XML namespace attribute jpa-operations, allowing you to provide a reference to custom implementations. For more details, please see http://static.springsource.org/spring-integration/docs/latest-ga/reference/html/jpa.html#jpa-namespace-support-common-attributes