making a post request to a rest api in camunda - rest

Question

I have a bpmn process/file where i intend to pass data in json format to a rest api via a post request. I have included the xml for the workflow below,
<?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_0wl4do2" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="5.6.0" modeler:executionPlatform="Camunda Cloud" modeler:executionPlatformVersion="8.1.0">
<bpmn:process id="Process_06dpeub" isExecutable="true">
<bpmn:sequenceFlow id="Flow_16ic7a9" sourceRef="StartEvent_1" targetRef="Activity_0nfsr66" />
<bpmn:endEvent id="Event_0q8baf4">
<bpmn:incoming>Flow_1gchegt</bpmn:incoming>
</bpmn:endEvent>
<bpmn:startEvent id="StartEvent_1" name="Employee record">
<bpmn:extensionElements />
<bpmn:outgoing>Flow_16ic7a9</bpmn:outgoing>
<bpmn:messageEventDefinition id="MessageEventDefinition_0lrekv7" messageRef="Message_1bc80bb" />
</bpmn:startEvent>
<bpmn:serviceTask id="Activity_16u939z" name="Add employee">
<bpmn:extensionElements>
<zeebe:ioMapping>
<zeebe:input source="=body" target="payload" />
<zeebe:output source="= result" target="employeeResult" />
</zeebe:ioMapping>
<zeebe:taskDefinition type="legacy" />
<zeebe:taskHeaders>
<zeebe:header key="url" value="/add/employee" />
<zeebe:header key="method" value="post" />
</zeebe:taskHeaders>
</bpmn:extensionElements>
<bpmn:incoming>Flow_09bylzt</bpmn:incoming>
<bpmn:outgoing>Flow_1gchegt</bpmn:outgoing>
</bpmn:serviceTask>
<bpmn:sequenceFlow id="Flow_1gchegt" sourceRef="Activity_16u939z" targetRef="Event_0q8baf4" />
<bpmn:serviceTask id="Activity_0nfsr66" name="Generate Payload">
<bpmn:extensionElements>
<zeebe:taskDefinition type="script" retries="2" />
<zeebe:taskHeaders>
<zeebe:header key="script" value="{ "employmentType": "LIMITED", "onboardingCheck": "false", "middleName": "ALI", "permittedDependents": "0", "personalEmail": "ayub_a#outlook.com", "businessRoleId": "1", "lastName": "Gama", "gradeId": "", "leaveGroupId": "1", "businessPhone": "0523308810", "leaveAllowance": "0", "personalAddress": "DUBAI", "employeeCode": "234234", "dateOfBirth": "1978-08-08", "firstName": "Alpha4", "citizenship_countryId": "1", "nationality": "Afghan", "salutation": "Mr", "personalPhone": "0523308810", "maritalStatus": "SINGLE", "leaveApprover": "1", "residencyVisaLocation": "DUBAI", "workingPatternId": "1", "businessEmail": "Alpha7#gmail.com", "preferredName": "Alpha4", "projectedEmploymentDate": "1978-08-08", "startDate": "2021-05-30", "currentYearLeaveAllocation": "0", "gender": "M" }" />
<zeebe:header key="language" value="mustache" />
</zeebe:taskHeaders>
<zeebe:ioMapping>
<zeebe:output source="=result" target="body" />
</zeebe:ioMapping>
</bpmn:extensionElements>
<bpmn:incoming>Flow_16ic7a9</bpmn:incoming>
<bpmn:outgoing>Flow_09bylzt</bpmn:outgoing>
</bpmn:serviceTask>
<bpmn:sequenceFlow id="Flow_09bylzt" sourceRef="Activity_0nfsr66" targetRef="Activity_16u939z" />
</bpmn:process>
<bpmn:message id="Message_1bc80bb" name="payload" />
<bpmndi:BPMNDiagram id="BPMNDiagram_1">
<bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_06dpeub">
<bpmndi:BPMNShape id="Event_0q8baf4_di" bpmnElement="Event_0q8baf4">
<dc:Bounds x="572" y="99" width="36" height="36" />
</bpmndi:BPMNShape>
<bpmndi:BPMNShape id="Event_1ovhyfk_di" bpmnElement="StartEvent_1">
<dc:Bounds x="162" y="99" width="36" height="36" />
<bpmndi:BPMNLabel>
<dc:Bounds x="138" y="142" width="84" height="14" />
</bpmndi:BPMNLabel>
</bpmndi:BPMNShape>
<bpmndi:BPMNShape id="BPMNShape_0veej1v" bpmnElement="Activity_16u939z">
<dc:Bounds x="420" y="77" width="100" height="80" />
</bpmndi:BPMNShape>
<bpmndi:BPMNShape id="BPMNShape_14olppq" bpmnElement="Activity_0nfsr66">
<dc:Bounds x="260" y="77" width="100" height="80" />
<bpmndi:BPMNLabel />
</bpmndi:BPMNShape>
<bpmndi:BPMNEdge id="Flow_16ic7a9_di" bpmnElement="Flow_16ic7a9">
<di:waypoint x="198" y="117" />
<di:waypoint x="260" y="117" />
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge id="Flow_1gchegt_di" bpmnElement="Flow_1gchegt">
<di:waypoint x="520" y="117" />
<di:waypoint x="572" y="117" />
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge id="Flow_09bylzt_di" bpmnElement="Flow_09bylzt">
<di:waypoint x="360" y="117" />
<di:waypoint x="420" y="117" />
</bpmndi:BPMNEdge>
</bpmndi:BPMNPlane>
</bpmndi:BPMNDiagram>
</bpmn:definitions>
Authentication is done server side and the logs do show that the request is received but nothing else, which is unhelpful. The url "/add/employee" gets preappended on the server side and becomes a valid url, so no issue there.
I am not certain that i modelled this correctly as the request gets successfully processed from postman whereas it fails when done via the workflow. The error observed on Operate is,
{
"name": "GeneralError",
"message": "Cannot read property 'id' of undefined",
"code": 500,
"className": "general-error",
"data": {},
"errors": {},
"status_code": 500,
"reason_code": "Internal Server Error"
}
Not much to go on, though i did initially get the same error on postman, it turns out some mandatory fields were missed in the payload. The payload would be what you would find in header script of the Generate Payload task.
What i am trying to get help on here is to see whether there is anything wrong with the bpmn model.