IllegalStateException: Failed to build variable mapping expression

[remcowesterhoud]

Describe the bug
Customer tries to deploy a process with a specific output variable mapping. Instead of breaking on validation, the deployment fails with an exception. This occurred in a production cluster.

https://console.cloud.google.com/errors/CPu8oYycy-7NWQ?service=zeebe&time=P7D&refresh=off&project=camunda-cloud-240911

To Reproduce

Deploy this process using Zeebe 1.2

<?xml version="1.0" encoding="UTF-8"?>
<bpmn:definitions xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:zeebe="http://camunda.org/schema/zeebe/1.0" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xmlns:modeler="http://camunda.org/schema/modeler/1.0" id="Definitions_1l8zqol" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="4.11.0" modeler:executionPlatform="Camunda Cloud" modeler:executionPlatformVersion="1.1.0">
  <bpmn:process id="Process_00dmwud" isExecutable="true">
    <bpmn:startEvent id="StartEvent_1">
      <bpmn:outgoing>Flow_0b71pnj</bpmn:outgoing>
    </bpmn:startEvent>
    <bpmn:endEvent id="Event_12llkjs">
      <bpmn:incoming>Flow_0hl1ts4</bpmn:incoming>
    </bpmn:endEvent>
    <bpmn:sequenceFlow id="Flow_0b71pnj" sourceRef="StartEvent_1" targetRef="Activity_13r0dql" />
    <bpmn:sequenceFlow id="Flow_0hl1ts4" sourceRef="Activity_13r0dql" targetRef="Event_12llkjs" />
    <bpmn:serviceTask id="Activity_13r0dql">
      <bpmn:extensionElements>
        <zeebe:taskDefinition type="type" retries="1" />
        <zeebe:ioMapping>
          <zeebe:output source="= result.CheckProcess.generalClassifications.operational[type=&#34;ACCOUNTING_PERIOD_VALIDATION&#34;][1]" target="accountingPeriodValidation.operational" />
          <zeebe:output source="= result.CheckProcess.generalClassifications.heating[type=&#34;ACCOUNTING_PERIOD_VALIDATION&#34;][1]" target="accountingPeriodValidation.heating" />
          <zeebe:output source="= result.CheckProcess.tenancy.utilityBill.operational" target="formalRequirementValidation.operational" />
          <zeebe:output source="= result.CheckProcess.tenancy.utilityBill.heating" target="formalRequirementValidation.heating" />
        </zeebe:ioMapping>
      </bpmn:extensionElements>
      <bpmn:incoming>Flow_0b71pnj</bpmn:incoming>
      <bpmn:outgoing>Flow_0hl1ts4</bpmn:outgoing>
    </bpmn:serviceTask>
  </bpmn:process>
  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_00dmwud">
      <bpmndi:BPMNEdge id="Flow_0hl1ts4_di" bpmnElement="Flow_0hl1ts4">
        <di:waypoint x="360" y="117" />
        <di:waypoint x="412" y="117" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0b71pnj_di" bpmnElement="Flow_0b71pnj">
        <di:waypoint x="215" y="117" />
        <di:waypoint x="260" y="117" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="StartEvent_1">
        <dc:Bounds x="179" y="99" width="36" height="36" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_12llkjs_di" bpmnElement="Event_12llkjs">
        <dc:Bounds x="412" y="99" width="36" height="36" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_0s27z46_di" bpmnElement="Activity_13r0dql">
        <dc:Bounds x="260" y="77" width="100" height="80" />
      </bpmndi:BPMNShape>
    </bpmndi:BPMNPlane>
  </bpmndi:BPMNDiagram>
</bpmn:definitions>

Expected behavior
A deployment validation would fail if the expression is invalid. Otherwise, the process should be deployed.

Log/Stacktrace

Full Stacktrace

java.lang.IllegalStateException: Failed to build variable mapping expression: failed to parse expression '{accountingPeriodValidation:if (accountingPeriodValidation = null) then {operational: result.CheckProcess.generalClassifications.operational[type="ACCOUNTING_PERIOD_VALIDATION"][1],heating: result.CheckProcess.generalClassifications.heating[type="ACCOUNTING_PERIOD_VALIDATION"][1]} else put all(accountingPeriodValidation,{operational: result.CheckProcess.generalClassifications.operational[type="ACCOUNTING_PERIOD_VALIDATION"][1],heating: result.CheckProcess.generalClassifications.heating[type="ACCOUNTING_PERIOD_VALIDATION"][1]}),formalRequirementValidation:if (formalRequirementValidation = null) then {operational: result.CheckProcess.tenancy.utilityBill.operational,heating: result.CheckProcess.tenancy.utilityBill.heating} else put all(formalRequirementValidation,{operational: result.CheckProcess.tenancy.utilityBill.operational,heating: result.CheckProcess.tenancy.utilityBill.heating})}': Expected (expressionWithContinuation | functionDefinition | forExpression | ifExpression | quantifiedExpression | expression2):1:1, found "{accountin"
	at io.camunda.zeebe.engine.processing.deployment.model.transformer.VariableMappingTransformer.parseExpression(VariableMappingTransformer.java:187) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.deployment.model.transformer.VariableMappingTransformer.transformOutputMappings(VariableMappingTransformer.java:93) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.deployment.model.transformer.FlowNodeTransformer.lambda$transformIoMappings$3(FlowNodeTransformer.java:72) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at java.util.Optional.map(Unknown Source) ~[?:?]
	at io.camunda.zeebe.engine.processing.deployment.model.transformer.FlowNodeTransformer.transformIoMappings(FlowNodeTransformer.java:70) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.deployment.model.transformer.FlowNodeTransformer.transform(FlowNodeTransformer.java:38) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.deployment.model.transformer.FlowNodeTransformer.transform(FlowNodeTransformer.java:21) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.deployment.model.transformation.TransformationVisitor.visit(TransformationVisitor.java:42) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.model.bpmn.traversal.TypeHierarchyVisitor.visit(TypeHierarchyVisitor.java:39) ~[zeebe-bpmn-model-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.model.bpmn.traversal.ModelWalker.walk(ModelWalker.java:61) ~[zeebe-bpmn-model-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.deployment.model.transformation.BpmnTransformer.transformDefinitions(BpmnTransformer.java:111) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.deployment.transform.DeploymentTransformer.transformResource(DeploymentTransformer.java:123) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.deployment.transform.DeploymentTransformer.transform(DeploymentTransformer.java:96) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.deployment.DeploymentCreateProcessor.processRecord(DeploymentCreateProcessor.java:100) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.streamprocessor.TypedRecordProcessor.processRecord(TypedRecordProcessor.java:54) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.streamprocessor.ProcessingStateMachine.lambda$processInTransaction$2(ProcessingStateMachine.java:258) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.db.impl.rocksdb.transaction.ZeebeTransaction.run(ZeebeTransaction.java:84) ~[zeebe-db-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.streamprocessor.ProcessingStateMachine.processInTransaction(ProcessingStateMachine.java:248) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.streamprocessor.ProcessingStateMachine.processEvent(ProcessingStateMachine.java:216) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.streamprocessor.ProcessingStateMachine.tryToReadNextEvent(ProcessingStateMachine.java:191) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.engine.processing.streamprocessor.ProcessingStateMachine.readNextEvent(ProcessingStateMachine.java:183) ~[zeebe-workflow-engine-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.util.sched.ActorJob.invoke(ActorJob.java:73) [zeebe-util-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.util.sched.ActorJob.execute(ActorJob.java:39) [zeebe-util-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.util.sched.ActorTask.execute(ActorTask.java:122) [zeebe-util-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.util.sched.ActorThread.executeCurrentTask(ActorThread.java:95) [zeebe-util-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.util.sched.ActorThread.doWork(ActorThread.java:78) [zeebe-util-1.2.1.jar:1.2.1]
	at io.camunda.zeebe.util.sched.ActorThread.run(ActorThread.java:192) [zeebe-util-1.2.1.jar:1.2.1]

Environment:

• OS: Camunda Cloud
• Zeebe Version: 1.2.1

[remcowesterhoud]

Expression = x.y[z = 0][1] causes this issue. = x[z = 0][1] works without a problem. = x.y[z = 0] also works without issue.
It seems to only go wrong when chaining square brackets (filter expressions?) on an inner value.

[Zelldon]

Would be interesting whether the complete bracket notation works ?
Like:

=['x']['y']['z = 0'][1]

https://support.smartbear.com/alertsite/docs/monitors/api/endpoint/jsonpath.html

[remcowesterhoud]

I've tried it using = x['y']['z = 0'][1], which does not cause the error, but fails on a validation. But just x['y'] also fails on the same validation, so I have a feeling this bracket notation is not supported at all.

[Zelldon]

afaik this is not valid: x['y'] it should be ['x']['y'] then.

[remcowesterhoud]

We need to start at a root object somewhere. In x['y]' I would say x is the root object and we try to access y in x.
With ['x']['y'] we are trying to access the field y in x in what root object?

In the link you send they also start with $ with refers to the root object or array.

Either way, I've tested it both and they both fail on the same validation.

[Zelldon]

Ok thanks for checking :D

[npepinpe]

Please open an issue in the FEEL scala project, and link it here. For Zeebe, for now, I will leave it in the backlog as it had very low impact.