If we want to check in our flow , weather payload is null or not , we can do it using MULE Expression Language .
#[payload == null]This was not working in MULE 3.1.1 , so we can try another expression like this :
#[payload is NullPayload]But , this condition also threw and Exception like this :
org.mule.api.MessagingException: Execution of the expression "payload is NullPayload" failed. (org.mule.api.expression.ExpressionRuntimeException). Message payload is of type: NullPayload
at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:35)
at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:43)
at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:43)
at org.mule.processor.chain.DefaultMessageProcessorChain.doProcess(DefaultMessageProcessorChain.java:93)
at org.mule.processor.chain.AbstractMessageProcessorChain.process(AbstractMessageProcessorChain.java:66)
at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:27)
at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:43)
at org.mule.processor.AbstractInterceptingMessageProcessorBase.processNext(AbstractInterceptingMessageProcessorBase.java:105)
at org.mule.interceptor.AbstractEnvelopeInterceptor.process(AbstractEnvelopeInterceptor.java:55)
at org.mule.processor.AsyncInterceptingMessageProcessor.processNextTimed(AsyncInterceptingMessageProcessor.java:118)
at org.mule.processor.AsyncInterceptingMessageProcessor$AsyncMessageProcessorWorker$1.process(AsyncInterceptingMessageProcessor.java:186)
at org.mule.processor.AsyncInterceptingMessageProcessor$AsyncMessageProcessorWorker$1.process(AsyncInterceptingMessageProcessor.java:179)
at org.mule.execution.ExecuteCallbackInterceptor.execute(ExecuteCallbackInterceptor.java:20)
at org.mule.execution.HandleExceptionInterceptor.execute(HandleExceptionInterceptor.java:34)
at org.mule.execution.HandleExceptionInterceptor.execute(HandleExceptionInterceptor.java:18)
at org.mule.execution.BeginAndResolveTransactionInterceptor.execute(BeginAndResolveTransactionInterceptor.java:58)
at org.mule.execution.ResolvePreviousTransactionInterceptor.execute(ResolvePreviousTransactionInterceptor.java:48)
at org.mule.execution.SuspendXaTransactionInterceptor.execute(SuspendXaTransactionInterceptor.java:54)
at org.mule.execution.ValidateTransactionalStateInterceptor.execute(ValidateTransactionalStateInterceptor.java:44)
at org.mule.execution.IsolateCurrentTransactionInterceptor.execute(IsolateCurrentTransactionInterceptor.java:44)
at org.mule.execution.ExternalTransactionInterceptor.execute(ExternalTransactionInterceptor.java:52)
at org.mule.execution.RethrowExceptionInterceptor.execute(RethrowExceptionInterceptor.java:32)
at org.mule.execution.RethrowExceptionInterceptor.execute(RethrowExceptionInterceptor.java:17)
at org.mule.execution.TransactionalErrorHandlingExecutionTemplate.execute(TransactionalErrorHandlingExecutionTemplate.java:113)
at org.mule.execution.TransactionalErrorHandlingExecutionTemplate.execute(TransactionalErrorHandlingExecutionTemplate.java:34)
at org.mule.processor.AsyncInterceptingMessageProcessor$AsyncMessageProcessorWorker.doRun(AsyncInterceptingMessageProcessor.java:178)
at org.mule.work.AbstractMuleEventWork.run(AbstractMuleEventWork.java:43)
at org.mule.work.WorkerContext.run(WorkerContext.java:311)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: org.mule.api.expression.ExpressionRuntimeException: Execution of the expression "payload is NullPayload" failed.
at org.mule.el.mvel.MVELExpressionLanguage.evaluateInternal(MVELExpressionLanguage.java:208)
at org.mule.el.mvel.MVELExpressionLanguage.evaluate(MVELExpressionLanguage.java:169)
at org.mule.expression.DefaultExpressionManager.evaluate(DefaultExpressionManager.java:234)
at org.mule.expression.DefaultExpressionManager.evaluateBoolean(DefaultExpressionManager.java:361)
at org.mule.routing.filters.ExpressionFilter.accept(ExpressionFilter.java:127)
at org.mule.routing.ChoiceRouter.selectProcessors(ChoiceRouter.java:35)
at org.mule.routing.AbstractSelectiveRouter.process(AbstractSelectiveRouter.java:194)
at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:27)
at org.mule.execution.MessageProcessorNotificationExecutionInterceptor.execute(MessageProcessorNotificationExecutionInterceptor.java:43)
at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:43)
at org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor.execute(ExceptionToMessagingExceptionExecutionInterceptor.java:27)
at org.mule.execution.MessageProcessorExecutionTemplate.execute(MessageProcessorExecutionTemplate.java:43)
... 23 more
Caused by: [Error: could not access: NullPayload; in class: null]
[Near : {... Unknown ....}]
^
[Line: 1, Column: 0]
at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getBeanProperty(ReflectiveAccessorOptimizer.java:611)
at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getBeanPropertyAO(ReflectiveAccessorOptimizer.java:439)
at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:353)
To resolve this , you have to tweak the expression a little bit like this :
#[payload is org.mule.transport.NullPayload]Post Comments And Suggestions !! MULE EXPRESSION LANGUAGE REF
