无法解析消费节点中参数的值

Question

在我的流程中，我将变量操作设置为：payload.operation，然后在消耗节点中我想获取它的值

变量值设置正确

我还包括我的流程的 xml：

<?xml version="1.0" encoding="UTF-8"?>

<mule xmlns:netsuite="http://www.mulesoft.org/schema/mule/netsuite" xmlns:wsc="http://www.mulesoft.org/schema/mule/wsc"
    xmlns:ee="http://www.mulesoft.org/schema/mule/ee/core"
    xmlns:db="http://www.mulesoft.org/schema/mule/db" xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.mulesoft.org/schema/mule/db http://www.mulesoft.org/schema/mule/db/current/mule-db.xsd
http://www.mulesoft.org/schema/mule/ee/core http://www.mulesoft.org/schema/mule/ee/core/current/mule-ee.xsd
http://www.mulesoft.org/schema/mule/wsc http://www.mulesoft.org/schema/mule/wsc/current/mule-wsc.xsd
http://www.mulesoft.org/schema/mule/netsuite http://www.mulesoft.org/schema/mule/netsuite/current/mule-netsuite.xsd">
    <http:listener-config name="HTTP_Listener_config" doc:name="HTTP Listener config" doc:id="a532976e-413b-4f47-bc8f-3e79e6de1417" >
        <http:listener-connection host="0.0.0.0" port="8081" />
    </http:listener-config>
    <db:config name="Database_Config" doc:name="Database Config" doc:id="276e5d43-bd49-4a82-b7c6-934288334aca" >
        <db:my-sql-connection host="mudb.learn.mulesoft.com" port="3306" user="mule" password="mule" database="training" />
    </db:config>
    <wsc:config name="Web_Service_Consumer_Config" doc:name="Web Service Consumer Config" doc:id="a5692620-4f26-4b11-be70-b822710d6c0d" >
        <wsc:connection wsdlLocation="http://dneonline.com/calculator.asmx?WSDL" service="Calculator" port="CalculatorSoap12" soapVersion="SOAP12" address="http://www.dneonline.com/calculator.asmx"/>
    </wsc:config>
    <flow name="api-accountsFlow" doc:id="7a942ae2-4422-46ba-b57d-38bd37ec9f82" >
        <http:listener doc:name="Get Accounts Listener" doc:id="a1873bcc-b9f1-4cf7-a405-a1c835cdf69c" config-ref="HTTP_Listener_config" path="/calculator" />
        <choice doc:name="Choice" doc:id="0b885797-7da1-4932-9183-869b5a670943" >
            <when expression='#[payload.operation=="Add" or payload.operation=="Subtract" or payload.operation=="Mul" or payload.operation=="Divide"]'>
                <set-variable value="#[payload.operation]" doc:name="Set Variable" doc:id="5c4da028-7ae8-43e6-ac35-84de6c3b4666" variableName="operation" />
                <ee:transform doc:name="Transform JSON Request to XML" doc:id="86f3eebe-0050-4800-9c08-7167ded759d9" >
                    <ee:message >
                        <ee:set-payload ><![CDATA[%dw 2.0
output application/xml
ns ns0 http://tempuri.org/
---
{
 ("ns0#" ++ vars.operation): { 
 
        ns0#intA: payload.val1,
        ns0#intB: payload.val2
    } 
}
]]></ee:set-payload>
                    </ee:message>
                </ee:transform>
                <wsc:consume doc:name="Consume" doc:id="091e6ca8-a78d-4a6f-b947-679235f7bfa4" config-ref="Web_Service_Consumer_Config" operation="#[vars.operation]"/>
                <ee:transform doc:name="Transform JSON Request to XML1" doc:id="6b77fd85-8af7-4f96-a299-2b64445ede0b" >
                    <ee:message >
                        <ee:set-payload ><![CDATA[%dw 2.0
output application/json
---
payload
 ]]></ee:set-payload>
                    </ee:message>
                </ee:transform>
            </when>
            <otherwise >
                <logger level="INFO" doc:name="Logger" doc:id="b4a8341c-a265-4c60-ab58-9b42d899c8fd" />
                <set-payload value="=== Operation Not Found ===" doc:name="Set Payload" doc:id="f8436921-0612-44b5-b12d-7dac7bfd7c2d" />
            </otherwise>
        </choice>
    </flow>
</mule>

当我运行我的流程时，我得到了

org.mule.runtime.module.extension.internal.runtime.ValueResolvingException: org.mule.runtime.module.extension.internal.runtime.ValueResolvingException: Unable to resolve value for the parameter: operation
    at org.mule.runtime.module.extension.internal.runtime.operation.OperationParameterValueResolver.getParameterValue(OperationParameterValueResolver.java:101)
    at org.mule.runtime.module.extension.internal.metadata.MetadataMediator.getMetadataKeyObjectValue(MetadataMediator.java:426)
    at org.mule.runtime.module.extension.internal.metadata.MetadataMediator.getMetadata(MetadataMediator.java:181)
    at org.mule.runtime.module.extension.internal.runtime.ExtensionComponent.lambda$getMetadata$21(ExtensionComponent.java:656)
    at org.mule.runtime.core.api.util.ExceptionUtils.tryExpecting(ExceptionUtils.java:224)
    at org.mule.runtime.core.api.util.ClassUtils.withContextClassLoader(ClassUtils.java:1102)
    at org.mule.runtime.core.api.util.ClassUtils.withContextClassLoader(ClassUtils.java:1020)
    at org.mule.runtime.module.extension.internal.runtime.ExtensionComponent.lambda$getMetadata$22(ExtensionComponent.java:655)
    at org.mule.runtime.module.extension.internal.runtime.ExtensionComponent.runWithMetadataContext(ExtensionComponent.java:793)
    at org.mule.runtime.module.extension.internal.runtime.ExtensionComponent.getMetadata(ExtensionComponent.java:654)
    at org.mule.runtime.metadata.internal.MuleMetadataService.lambda$getComponentMetadata$7(MuleMetadataService.java:218)
    at org.mule.runtime.metadata.internal.MuleMetadataService.exceptionHandledMetadataFetch(MuleMetadataService.java:174)
    at org.mule.runtime.metadata.internal.MuleMetadataService.getComponentMetadata(MuleMetadataService.java:217)
    at org.mule.runtime.metadata.internal.MuleMetadataService.getOperationMetadata(MuleMetadataService.java:116)
    at org.mule.runtime.config.internal.bean.lazy.LazyMetadataService.lambda$getOperationMetadata$4(LazyMetadataService.java:100)
    at java.util.Optional.orElseGet(Optional.java:267)
    at org.mule.runtime.config.internal.bean.lazy.LazyMetadataService.getOperationMetadata(LazyMetadataService.java:100)
    at com.mulesoft.agent.services.metadata.MuleAgentMetadataService.lambda$getOperationMetadata$2(MuleAgentMetadataService.java:75)
    at com.mulesoft.agent.services.metadata.MuleAgentMetadataService.withMetadataService(MuleAgentMetadataService.java:145)
    at com.mulesoft.agent.services.metadata.MuleAgentMetadataService.getOperationMetadata(MuleAgentMetadataService.java:75)
    at com.mulesoft.agent.external.handlers.metadata.MetadataRequestHandler.lambda$getOperationMetadata$3(MetadataRequestHandler.java:206)
    at com.mulesoft.agent.util.ResponseHelper.response(ResponseHelper.java:88)
    at com.mulesoft.agent.external.handlers.metadata.MetadataRequestHandler.getOperationMetadata(MetadataRequestHandler.java:204)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory.lambda$static$0(ResourceMethodInvocationHandlerFactory.java:52)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:134)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:177)
    at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:176)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:81)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:478)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:400)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:81)
    at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:256)
    at org.glassfish.jersey.internal.Errors$1.call(Errors.java:248)
    at org.glassfish.jersey.internal.Errors$1.call(Errors.java:244)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:292)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:274)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:244)
    at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:265)
    at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:235)
    at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:684)
    at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:394)
    at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:346)
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:358)
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:311)
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:205)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:799)
    at org.eclipse.jetty.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1656)
    at com.mulesoft.agent.rest.RequestLoggingFilter.doFilter(RequestLoggingFilter.java:95)
    at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
    at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1626)
    at com.mulesoft.agent.rest.AuthorizationFilter.doFilter(AuthorizationFilter.java:49)
    at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
    at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1626)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:552)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1440)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:505)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1355)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
    at org.eclipse.jetty.server.Server.handle(Server.java:516)
    at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:487)
    at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:732)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:479)
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:277)
    at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311)
    at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105)
    at org.eclipse.jetty.io.ChannelEndPoint$1.run(ChannelEndPoint.java:104)
    at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:338)
    at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:315)
    at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:173)
    at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:131)
    at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:409)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:883)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1034)
    at java.lang.Thread.run(Thread.java:750)
Caused by: java.lang.IllegalArgumentException: Required parameter 'operation' was assigned with value '#[vars.operation]' which resolved to null. Required parameters need to be assigned with non null values
    at org.mule.runtime.module.extension.internal.runtime.resolver.RequiredParameterValueResolverWrapper.resolve(RequiredParameterValueResolverWrapper.java:67)
    at org.mule.runtime.module.extension.internal.runtime.LazyExecutionContext.lambda$lazy$1(LazyExecutionContext.java:61)
    at org.mule.runtime.core.api.util.func.CheckedSupplier.get(CheckedSupplier.java:25)
    at org.mule.runtime.api.util.LazyValue.get(LazyValue.java:75)
    at org.mule.runtime.module.extension.internal.runtime.LazyExecutionContext.getParameter(LazyExecutionContext.java:78)
    at org.mule.runtime.module.extension.internal.runtime.operation.OperationParameterValueResolver.lambda$getParameterValue$1(OperationParameterValueResolver.java:95)
    at java.util.Optional.orElseGet(Optional.java:267)
    at org.mule.runtime.module.extension.internal.runtime.operation.OperationParameterValueResolver.getParameterValue(OperationParameterValueResolver.java:78)
    ... 81 more

经过一些测试，我认为问题可能出在这部分：(“ns0#”++ vars.operation)：因为从邮递员那里我得到这个错误：

使用操作 [Subtract] 时出错，请求正文不是有效的 XML

Answer 1

我怀疑因为变量是用 JSON 负载中的值设置的，所以它可能会让 Mule 感到困惑。该图显示变量

operation

是一个 JSON。尝试将其指定为 Java 输出以从字符串中删除 JSON 格式：

<set-variable value="#[output application/java --- payload.operation]" doc:name="Set Variable" doc:id="5c4da028-7ae8-43e6-ac35-84de6c3b4666" variableName="operation" />