Cannot convert value of type [com.sun.proxy.$Proxy32 ScopedObject

Question

I am using spring batch, below are the configurations.

<beans:bean id="symfonyJob" class="com.st.symfony.Symfony"
    p:dir="${symfony.dir}" p:consolePath="${symfony.console.path}"
    p:strUtil-ref="strUtil" p:logFilePath="${batch.log.file.path}.#{jobParameters[batch_id]}" scope="step"/>


<beans:bean id="importExchangesItemWriter"
    class="com.st.batch.foundation.ImportExchangesItemWriter"
    p:symfony-ref="symfonyJob" p:replyTimeout="${import.exchanges.reply.timeout}" scope="step"/>

<beans:bean id="importExchangesFileItemReader"
    class="org.springframework.batch.item.file.MultiThreadedFlatFileItemReader"
    p:resource="file:${spring.tmp.batch.dir}/#{jobParameters[batch_id]}/exchanges.txt"
    p:lineMapper-ref="stLineMapper" p:startAt="#{stepExecutionContext['startAt']}"
    p:maxItemCount="#{stepExecutionContext['itemsCount']}" scope="step" />

<step id="importExchangesStep">
    <tasklet transaction-manager="transactionManager">
        <chunk reader="importExchangesFileItemReader" writer="importExchangesItemWriter"
            commit-interval="${import.exchanges.commit.interval}" />
    </tasklet>
</step>

<job id="importExchangesJob" restartable="true">

    <step id="importExchangesStep.master">
        <partition partitioner="importExchangesPartitioner"
            handler="importExchangesPartitionHandler" />
    </step>

</job>

Everything was working before I change the scope of symfonyJob and importExchangesItemWriter to scope="step". As soon as I changed scope, I am getting

ERROR: org.springframework.batch.core.step.AbstractStep - Encountered an error executing step importExchangesStep in job importExchangesJob
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scopedTarget.importExchangesItemWriter' defined in file [/home/vishal/install/sts-bundle/vfabric-tc-server-developer-2.9.6.RELEASE/base-instance/wtpwebapps/spring/WEB-INF/classes/META-INF/spring/batch/jobs/foundation/steps/import-exchanges.xml]: Initialization of bean failed; nested exception is org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'com.sun.proxy.$Proxy32 implementing org.springframework.aop.scope.ScopedObject,java.io.Serializable,org.springframework.aop.framework.AopInfrastructureBean,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised' to required type 'com.st.symfony.Symfony' for property 'symfony'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [com.sun.proxy.$Proxy32 implementing org.springframework.aop.scope.ScopedObject,java.io.Serializable,org.springframework.aop.framework.AopInfrastructureBean,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised] to required type [com.st.symfony.Symfony] for property 'symfony': no matching editors or conversion strategy found
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:532)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:461)
    at org.springframework.beans.factory.support.AbstractBeanFactory$2.getObject(AbstractBeanFactory.java:333)
    at org.springframework.batch.core.scope.StepScope.get(StepScope.java:110)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:329)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.aop.target.SimpleBeanTargetSource.getTarget(SimpleBeanTargetSource.java:34)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:184)
    at com.sun.proxy.$Proxy26.write(Unknown Source)
    at org.springframework.batch.core.step.item.SimpleChunkProcessor.writeItems(SimpleChunkProcessor.java:175)
    at org.springframework.batch.core.step.item.SimpleChunkProcessor.doWrite(SimpleChunkProcessor.java:151)
    at org.springframework.batch.core.step.item.SimpleChunkProcessor.write(SimpleChunkProcessor.java:274)
    at org.springframework.batch.core.step.item.SimpleChunkProcessor.process(SimpleChunkProcessor.java:199)
    at org.springframework.batch.core.step.item.ChunkOrientedTasklet.execute(ChunkOrientedTasklet.java:75)
    at org.springframework.batch.core.step.tasklet.TaskletStep$ChunkTransactionCallback.doInTransaction(TaskletStep.java:402)
    at org.springframework.batch.core.step.tasklet.TaskletStep$ChunkTransactionCallback.doInTransaction(TaskletStep.java:326)
    at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:131)
    at org.springframework.batch.core.step.tasklet.TaskletStep$2.doInChunkContext(TaskletStep.java:267)
    at org.springframework.batch.core.scope.context.StepContextRepeatCallback.doInIteration(StepContextRepeatCallback.java:77)
    at org.springframework.batch.repeat.support.RepeatTemplate.getNextResult(RepeatTemplate.java:368)
    at org.springframework.batch.repeat.support.RepeatTemplate.executeInternal(RepeatTemplate.java:215)
    at org.springframework.batch.repeat.support.RepeatTemplate.iterate(RepeatTemplate.java:144)
    at org.springframework.batch.core.step.tasklet.TaskletStep.doExecute(TaskletStep.java:253)
    at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:198)
    at org.springframework.batch.integration.partition.StepExecutionRequestHandler.handle(StepExecutionRequestHandler.java:64)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.springframework.expression.spel.support.ReflectiveMethodExecutor.execute(ReflectiveMethodExecutor.java:69)
    at org.springframework.expression.spel.ast.MethodReference$MethodValueRef.getValue(MethodReference.java:97)
    at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:81)
    at org.springframework.expression.spel.ast.SpelNodeImpl.getTypedValue(SpelNodeImpl.java:102)
    at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:103)
    at org.springframework.integration.util.AbstractExpressionEvaluator.evaluateExpression(AbstractExpressionEvaluator.java:126)
    at org.springframework.integration.util.MessagingMethodInvokerHelper.processInternal(MessagingMethodInvokerHelper.java:227)
    at org.springframework.integration.util.MessagingMethodInvokerHelper.process(MessagingMethodInvokerHelper.java:127)
    at org.springframework.integration.handler.MethodInvokingMessageProcessor.processMessage(MethodInvokingMessageProcessor.java:73)
    at org.springframework.integration.handler.ServiceActivatingHandler.handleRequestMessage(ServiceActivatingHandler.java:67)
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:134)
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:73)
    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.core.MessagingTemplate.doSend(MessagingTemplate.java:288)
    at org.springframework.integration.core.MessagingTemplate.doSendAndReceive(MessagingTemplate.java:318)
    at org.springframework.integration.core.MessagingTemplate.sendAndReceive(MessagingTemplate.java:239)
    at org.springframework.integration.gateway.MessagingGatewaySupport.doSendAndReceive(MessagingGatewaySupport.java:233)
    at org.springframework.integration.gateway.MessagingGatewaySupport.sendAndReceiveMessage(MessagingGatewaySupport.java:207)
    at org.springframework.integration.amqp.inbound.AmqpInboundGateway.access$200(AmqpInboundGateway.java:47)
    at org.springframework.integration.amqp.inbound.AmqpInboundGateway$1.onMessage(AmqpInboundGateway.java:87)
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:693)
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:586)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$001(SimpleMessageListenerContainer.java:75)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$1.invokeListener(SimpleMessageListenerContainer.java:154)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.invokeListener(SimpleMessageListenerContainer.java:1113)
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:559)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:904)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:888)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$500(SimpleMessageListenerContainer.java:75)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:989)
    at java.lang.Thread.run(Thread.java:724)
Caused by: org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'com.sun.proxy.$Proxy32 implementing org.springframework.aop.scope.ScopedObject,java.io.Serializable,org.springframework.aop.framework.AopInfrastructureBean,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised' to required type 'com.st.symfony.Symfony' for property 'symfony'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [com.sun.proxy.$Proxy32 implementing org.springframework.aop.scope.ScopedObject,java.io.Serializable,org.springframework.aop.framework.AopInfrastructureBean,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised] to required type [com.st.symfony.Symfony] for property 'symfony': no matching editors or conversion strategy found
    at org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:463)
    at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:494)
    at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:488)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.convertForProperty(AbstractAutowireCapableBeanFactory.java:1437)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1396)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1132)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:522)
    ... 62 more
Caused by: java.lang.IllegalStateException: Cannot convert value of type [com.sun.proxy.$Proxy32 implementing org.springframework.aop.scope.ScopedObject,java.io.Serializable,org.springframework.aop.framework.AopInfrastructureBean,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised] to required type [com.st.symfony.Symfony] for property 'symfony': no matching editors or conversion strategy found
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:264)
    at org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:448)
    ... 68 more

It was working even though reader had scope step but as soon as I add it to writer, I started getting this error.

Answer 1

I saw this error with a slightly different scenario:

I did not follow the proper pattern for HibernateDAO bean, it required interface with methods and to pass the interface type in to the service layer spring bean as property instead of the DAO implementation class.

applicationContext.xml

<bean id="myEntityDAO" class="com.me.etc.MyEntityDAOImpl" parent="hibernateDAO"/>

<bean id="myEntityService class="com.me.etc.MyEntityServiceImpl">
  <property name="myEntityDAO" ref="myEntityDAO" />
</bean>

MyEntityServiceImpl.java

class MyEntityServiceImpl extends MyEntityService {
  .
  .
  .
  // I got the error when I had this property of class MyEntityDAOImpl
  private MyEntityDAOInterface myEntityDAO;

  // changed the setter as well to match
  @Required
  public setMyEntityDAO(MyEntityDAOInterface myEntityDAO) {
     this.myEntityDAO = myEntityDAO;
  }
  .
  .
  .
}

Spring wanted the interface to pass in, instead of the implemented class file which caused the "Cannot convert value of type" error.

Answer 2

You need to expose <aop:scoped-proxy proxy-target-class="true" /> for symfonyJob bean because standard proxy creation expose interfaces and not concrete class (as you need,because ImportExchangesItemWriter.setSymfony() accept - for sure - a com.st.symfony.Symfony parameter and not an interface).
You can have more info about proxy creation mechanisms googling for "aop proxytargetclass".