Camunda: How to get DMN to emit two variable/values to context of BPM workflow?

I want the two output values from DMN row, be sent to BPMN context, e.g DMN.output.var1=val1, DMN.output.var2=val2.

Input: (SPACE=LAW, THING=VANDALISM)

Output: (ROUT_TO_DEPT=BY_LAW, OUT_CATEGORY=INSPECTION)

These two variables must be in context, and available to next step in BPMN.

However I'm getting an error, how to make it happen?

DMN

Error

Stacktrace:

Caused by: org.camunda.bpm.engine.ProcessEngineException: ENGINE-22002 The decision result mapper 'CollectEntriesDecisionResultMapper{}' failed to process '[{ROUT_TO_DEPT=Value 'BY_LAW' of type 'PrimitiveValueType[string]', isTransient=false, OUT_CATETORY=Value 'INSPECTION' of type 'PrimitiveValueType[string]', isTransient=false}]'. The decision outputs should only contains values for one output name but found '[ROUT_TO_DEPT, OUT_CATETORY]'.
        at org.camunda.bpm.engine.impl.dmn.DecisionLogger.decisionResultCollectMappingException(DecisionLogger.java:44)
        at org.camunda.bpm.engine.impl.dmn.result.CollectEntriesDecisionResultMapper.mapDecisionResult(CollectEntriesDecisionResultMapper.java:46)
        at org.camunda.bpm.engine.impl.util.DecisionEvaluationUtil.evaluateDecision(DecisionEvaluationUtil.java:79)
        at org.camunda.bpm.engine.impl.bpmn.behavior.DmnBusinessRuleTaskActivityBehavior$1.call(DmnBusinessRuleTaskActivityBehavior.java:56)
        at org.camunda.bpm.engine.impl.bpmn.behavior.DmnBusinessRuleTaskActivityBehavior$1.call(DmnBusinessRuleTaskActivityBehavior.java:53)
        at org.camunda.bpm.engine.impl.bpmn.behavior.AbstractBpmnActivityBehavior.executeWithErrorPropagation(AbstractBpmnActivityBehavior.java:90)
        at org.camunda.bpm.engine.impl.bpmn.behavior.DmnBusinessRuleTaskActivityBehavior.execute(DmnBusinessRuleTaskActivityBehavior.java:53)
        at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationActivityExecute$2.callback(PvmAtomicOperationActivityExecute.java:61)
        at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationActivityExecute$2.callback(PvmAtomicOperationActivityExecute.java:50)
        at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl.continueIfExecutionDoesNotAffectNextOperation(PvmExecutionImpl.java:1996)
        at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationActivityExecute.execute(PvmAtomicOperationActivityExecute.java:42)
        at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationActivityExecute.execute(PvmAtomicOperationActivityExecute.java:31)
        at org.camunda.bpm.engine.impl.interceptor.AtomicOperationInvocation.execute(AtomicOperationInvocation.java:96)
        at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.invokeNext(CommandInvocationContext.java:128)

I tried to make it as resultList variable, however what I wanted is two output variables - a tuple.

Edit 1: If I choose "singleResult" option, I'm able to get it as a map in one single variable, however I want TWO varibles going to next STEP in a BPMN flow.

Solution

The mapping to resultList is used to map a list of rows with multiple output columns. Switching to singleResult was the right direction. You are using a hit policy "First" (one rule/ row only), so the map decision result property can only be singleEntry (one output column) or singleResult (several output columns).

After mapping the decision result to a singleResult, you can use the Input/Output tab in the property panel to map the result entries to process variables:

In the text field of the output mapping you can use unified expression language, e.g. ${deptRoureDetail.get('ROUT_TO_DEPT')}

to access the result variable (in your case deptRoutDetail) of type Map and access the desired fields (ROUT_TO_DEPT, etc) by their keys.

Full example:

a) BPMN

<?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:camunda="http://camunda.org/schema/1.0/bpmn" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" id="Definitions_17ij5vv" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="3.5.0">
  <bpmn:process id="Process_TwoOutputs" name="Two Outputs" isExecutable="true">
    <bpmn:startEvent id="StartEvent_1">
      <bpmn:extensionElements>
        <camunda:formData>
          <camunda:formField id="customer" label="Customer" type="string" defaultValue="Miller" />
        </camunda:formData>
      </bpmn:extensionElements>
      <bpmn:outgoing>SequenceFlow_1uzzene</bpmn:outgoing>
    </bpmn:startEvent>
    <bpmn:sequenceFlow id="SequenceFlow_1uzzene" sourceRef="StartEvent_1" targetRef="Task_EvaluteRules" />
    <bpmn:businessRuleTask id="Task_EvaluteRules" name="Evalute Rules" camunda:resultVariable="result" camunda:decisionRef="Decision_twoOutputs" camunda:mapDecisionResult="singleResult">
      <bpmn:extensionElements>
        <camunda:inputOutput>
          <camunda:outputParameter name="blacklisted">${result.get('blacklistedCustomer')}</camunda:outputParameter>
          <camunda:outputParameter name="pep">${result.get('pepCustomer')}</camunda:outputParameter>
        </camunda:inputOutput>
      </bpmn:extensionElements>
      <bpmn:incoming>SequenceFlow_1uzzene</bpmn:incoming>
      <bpmn:outgoing>SequenceFlow_10pcdah</bpmn:outgoing>
    </bpmn:businessRuleTask>
    <bpmn:sequenceFlow id="SequenceFlow_10pcdah" sourceRef="Task_EvaluteRules" targetRef="Task_00rrqy1" />
    <bpmn:endEvent id="EndEvent_0f61xh5">
      <bpmn:incoming>SequenceFlow_1fsnixe</bpmn:incoming>
    </bpmn:endEvent>
    <bpmn:sequenceFlow id="SequenceFlow_1fsnixe" sourceRef="Task_00rrqy1" targetRef="EndEvent_0f61xh5" />
    <bpmn:scriptTask id="Task_00rrqy1" name="Print both variables" scriptFormat="javascript">
      <bpmn:incoming>SequenceFlow_10pcdah</bpmn:incoming>
      <bpmn:outgoing>SequenceFlow_1fsnixe</bpmn:outgoing>
      <bpmn:script>print("blacklisted: " + blacklisted);
print("pep: " + pep);</bpmn:script>
    </bpmn:scriptTask>
  </bpmn:process>
  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_TwoOutputs">
      <bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="StartEvent_1">
        <dc:Bounds x="179" y="99" width="36" height="36" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge id="SequenceFlow_1uzzene_di" bpmnElement="SequenceFlow_1uzzene">
        <di:waypoint x="215" y="117" />
        <di:waypoint x="270" y="117" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNShape id="BusinessRuleTask_1oc25xp_di" bpmnElement="Task_EvaluteRules">
        <dc:Bounds x="270" y="77" width="100" height="80" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge id="SequenceFlow_10pcdah_di" bpmnElement="SequenceFlow_10pcdah">
        <di:waypoint x="370" y="117" />
        <di:waypoint x="430" y="117" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNShape id="EndEvent_0f61xh5_di" bpmnElement="EndEvent_0f61xh5">
        <dc:Bounds x="592" y="99" width="36" height="36" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge id="SequenceFlow_1fsnixe_di" bpmnElement="SequenceFlow_1fsnixe">
        <di:waypoint x="530" y="117" />
        <di:waypoint x="592" y="117" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNShape id="ScriptTask_1xt3142_di" bpmnElement="Task_00rrqy1">
        <dc:Bounds x="430" y="77" width="100" height="80" />
      </bpmndi:BPMNShape>
    </bpmndi:BPMNPlane>
  </bpmndi:BPMNDiagram>
</bpmn:definitions>

b) DMN

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/DMN/20151101/dmn.xsd" xmlns:biodi="http://bpmn.io/schema/dmn/biodi/1.0" id="Definitions_0cib9be" name="DRD" namespace="http://camunda.org/schema/1.0/dmn" exporter="Camunda Modeler" exporterVersion="3.5.0">
  <decision id="Decision_twoOutputs" name="Two Outputs">
    <extensionElements>
      <biodi:bounds x="150" y="150" width="180" height="80" />
    </extensionElements>
    <decisionTable id="decisionTable_1">
      <input id="input_1" label="Customer Name">
        <inputExpression id="inputExpression_1" typeRef="string">
          <text>customer</text>
        </inputExpression>
      </input>
      <output id="output_1" label="blacklisted" name="blacklistedCustomer" typeRef="string" />
      <output id="OutputClause_18xxjii" label="Politically Exposed Person" name="pepCustomer" typeRef="boolean" />
      <rule id="DecisionRule_0qg0ni4">
        <inputEntry id="UnaryTests_1i6rkew">
          <text>"Miller"</text>
        </inputEntry>
        <outputEntry id="LiteralExpression_12xbrsq">
          <text>"clear"</text>
        </outputEntry>
        <outputEntry id="LiteralExpression_1obxdmm">
          <text>false</text>
        </outputEntry>
      </rule>
      <rule id="DecisionRule_06aolv9">
        <inputEntry id="UnaryTests_0oeomwy">
          <text>"Smith"</text>
        </inputEntry>
        <outputEntry id="LiteralExpression_1xobooq">
          <text>"clear"</text>
        </outputEntry>
        <outputEntry id="LiteralExpression_0sok0z4">
          <text>true</text>
        </outputEntry>
      </rule>
      <rule id="DecisionRule_0ki09vh">
        <inputEntry id="UnaryTests_096b0z2">
          <text>"Jones"</text>
        </inputEntry>
        <outputEntry id="LiteralExpression_11x7v5h">
          <text>"blacklisted"</text>
        </outputEntry>
        <outputEntry id="LiteralExpression_1nit6ye">
          <text>false</text>
        </outputEntry>
      </rule>
      <rule id="DecisionRule_0tifgq8">
        <inputEntry id="UnaryTests_0fqbez3">
          <text>"Doe"</text>
        </inputEntry>
        <outputEntry id="LiteralExpression_0yghulu">
          <text>"blacklisted"</text>
        </outputEntry>
        <outputEntry id="LiteralExpression_1j2jmlj">
          <text>true</text>
        </outputEntry>
      </rule>
    </decisionTable>
  </decision>
</definitions>

c) jUnit Test

import org.camunda.bpm.dmn.engine.DmnDecisionTableResult;
import org.camunda.bpm.engine.runtime.ProcessInstance;
import org.camunda.bpm.engine.test.Deployment;
import org.camunda.bpm.engine.test.ProcessEngineRule;
import org.camunda.bpm.engine.variable.Variables;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;

import java.util.Map;

import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.entry;
import static org.camunda.bpm.engine.test.assertions.ProcessEngineTests.init;
import static org.camunda.bpm.engine.test.assertions.bpmn.BpmnAwareTests.decisionService;

public class DMNUnitTest {

    @Rule
    public ProcessEngineRule rule = new ProcessEngineRule();

    @Before
    public void setup() {
        init(rule.getProcessEngine());
    }

    @Test
    @Deployment(resources = {"twoOutputs.dmn"})
    public void testNoFlags() {
        Map<String, Object> variables = Variables.createVariables().putValue("customer", "Miller");
        DmnDecisionTableResult results = decisionService().evaluateDecisionTableByKey("Decision_twoOutputs", variables);
        assertThat(results).hasSize(1);
        assertThat(results.getSingleResult())
                .contains(entry("blacklistedCustomer", "clear"))
                .contains(entry("pepCustomer", false));
    }

    @Test
    @Deployment(resources = {"twoOutputs.dmn", "twoOutputs.bpmn"})
    public void testProcessWithtwoDecisionOutputs() {
        Map<String, Object> variables = Variables.createVariables().putValue("customer", "Miller");
        ProcessInstance pi =  rule.getRuntimeService().startProcessInstanceByKey("Process_TwoOutputs", variables);
        org.camunda.bpm.engine.test.assertions.bpmn.BpmnAwareTests.assertThat(pi).hasVariables("blacklisted","pep");

    }
}