Not able to retrieve Form variables via getStartFormVariables by processDefinitionId

Vinodlouis · March 13, 2017, 5:34am

I’m using camunda jars and working on an experimental case to build custom forms for the processes. I read the docs and learnt that form variables can be fetched from form service getStartFormVariables method. consider the below code:

String processDefinitionId = "generatedFormsQuickstart:1:2503";
Gson gson = new Gson();
String result = gson.toJson(processEngine.getFormService().getStartFormVariables(processDefinitionId));
System.out.println(result);
result = gson.toJson(processEngine.getFormService().getRenderedStartForm(processDefinitionId));
System.out.println(result);

Here in result the first sysout prints {} whereas the second prints the whole form"\u003cform name\u003d\"generatedFo... with all variables.

I’m confused of why variables are not being retrieved but the built forms are retrieved.

Please guide

roman.smirnov · March 13, 2017, 9:45am

Hi @Vinodlouis,

Could you please share your BPMN?

Cheers,
Roman

Vinodlouis · March 13, 2017, 9:49am

<?xml version="1.0" encoding="UTF-8"?>
<bpmn2:definitions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:bpmn2="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:camunda="http://activiti.org/bpmn" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xsi:schemaLocation="http://www.omg.org/spec/BPMN/20100524/MODEL BPMN20.xsd" id="_r7y_gEa-EeO5NO3lqhkDkg" targetNamespace="http://activiti.org/bpmn">
  <bpmn2:process id="generatedFormsQuickstart" name="Generated Forms Quickstart" isExecutable="true">
    <bpmn2:startEvent id="StartEvent_1" name="Loan Request &#xD;&#xA;Received">
      <bpmn2:extensionElements>
        <camunda:formData>
          <camunda:formField id="firstname" label="Firstname" type="string">
            <camunda:validation>
              <camunda:constraint name="maxlength" config="25"/>
              <camunda:constraint name="required"/>
            </camunda:validation>
          </camunda:formField>
          <camunda:formField id="lastname" label="Lastname" type="string">
            <camunda:validation>
              <camunda:constraint name="maxlength" config="25"/>
              <camunda:constraint name="required"/>
            </camunda:validation>
          </camunda:formField>
          <camunda:formField id="netIncome" label="Net Income" type="long">
            <camunda:validation>
              <camunda:constraint name="required"/>
            </camunda:validation>
          </camunda:formField>
          <camunda:formField id="loanAmmount" label="Loan Ammount" type="long">
            <camunda:validation>
              <camunda:constraint name="required"/>
            </camunda:validation>
          </camunda:formField>
          <camunda:formField id="loanType" label="Loan Type" type="enum">
            <camunda:validation>
              <camunda:constraint name="required"/>
            </camunda:validation>
            <camunda:value id="mortage" name="Mortage Loan (5%)"/>
            <camunda:value id="cashAdvance" name="Cash Advance (10%)"/>
          </camunda:formField>
        </camunda:formData>
      </bpmn2:extensionElements>
      <bpmn2:outgoing>SequenceFlow_1</bpmn2:outgoing>
    </bpmn2:startEvent>
    <bpmn2:sequenceFlow id="SequenceFlow_1" sourceRef="StartEvent_1" targetRef="UserTask_1"/>
    <bpmn2:endEvent id="EndEvent_1" name="Done">
      <bpmn2:incoming>SequenceFlow_3</bpmn2:incoming>
    </bpmn2:endEvent>
    <bpmn2:userTask id="UserTask_1" name="Approve Request">
      <bpmn2:extensionElements>
        <camunda:formData>
          <camunda:formField id="firstname" label="Firstname" type="string">
            <camunda:validation>
              <camunda:constraint name="readonly"/>
            </camunda:validation>
          </camunda:formField>
          <camunda:formField id="lastname" label="Lastname" type="string">
            <camunda:validation>
              <camunda:constraint name="readonly"/>
            </camunda:validation>
          </camunda:formField>
          <camunda:formField id="netIncome" label="Net Income" type="long">
            <camunda:validation>
              <camunda:constraint name="readonly"/>
            </camunda:validation>
          </camunda:formField>
          <camunda:formField id="loanAmmount" label="Loan Ammount" type="long">
            <camunda:validation>
              <camunda:constraint name="readonly"/>
            </camunda:validation>
          </camunda:formField>
          <camunda:formField id="loanType" label="Loan Type" type="string">
            <camunda:validation>
              <camunda:constraint name="readonly"/>
            </camunda:validation>
          </camunda:formField>
          <camunda:formField id="approved" label="Approve?" type="boolean"/>       
        </camunda:formData>
      </bpmn2:extensionElements>
      <bpmn2:incoming>SequenceFlow_1</bpmn2:incoming>
      <bpmn2:outgoing>SequenceFlow_3</bpmn2:outgoing>
    </bpmn2:userTask>
    <bpmn2:sequenceFlow id="SequenceFlow_3" sourceRef="UserTask_1" targetRef="EndEvent_1"/>
  </bpmn2:process>
  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_1">
      <bpmndi:BPMNShape id="_BPMNShape_StartEvent_3" bpmnElement="StartEvent_1">
        <dc:Bounds height="36.0" width="36.0" x="82.0" y="118.0"/>
        <bpmndi:BPMNLabel>
          <dc:Bounds height="38.0" width="100.0" x="50.0" y="159.0"/>
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="_BPMNShape_UserTask_3" bpmnElement="UserTask_1">
        <dc:Bounds height="80.0" width="100.0" x="204.0" y="96.0"/>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge id="BPMNEdge_SequenceFlow_1" bpmnElement="SequenceFlow_1" sourceElement="_BPMNShape_StartEvent_3" targetElement="_BPMNShape_UserTask_3">
        <di:waypoint xsi:type="dc:Point" x="118.0" y="136.0"/>
        <di:waypoint xsi:type="dc:Point" x="204.0" y="136.0"/>
        <bpmndi:BPMNLabel>
          <dc:Bounds height="0.0" width="0.0" x="143.0" y="136.0"/>
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNShape id="_BPMNShape_EndEvent_8" bpmnElement="EndEvent_1">
        <dc:Bounds height="36.0" width="36.0" x="366.0" y="118.0"/>
        <bpmndi:BPMNLabel>
          <dc:Bounds height="22.0" width="36.0" x="366.0" y="159.0"/>
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge id="BPMNEdge_SequenceFlow_3" bpmnElement="SequenceFlow_3" sourceElement="_BPMNShape_UserTask_3" targetElement="_BPMNShape_EndEvent_8">
        <di:waypoint xsi:type="dc:Point" x="304.0" y="136.0"/>
        <di:waypoint xsi:type="dc:Point" x="366.0" y="136.0"/>
        <bpmndi:BPMNLabel>
          <dc:Bounds height="0.0" width="0.0" x="329.0" y="136.0"/>
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNEdge>
    </bpmndi:BPMNPlane>
  </bpmndi:BPMNDiagram>
</bpmn2:definitions>

roman.smirnov · March 13, 2017, 9:57am

Hi @Vinodlouis,

When I execute processEngine.getFormService().getStartFormVariables(...) then I get the variables defined as form fields.

I am not aware of Gson, what does gson.toJson(...) do? Could you please just execute processEngine.getFormService().getStartFormVariables(processDefinitionId) and check whether the expected variables are returned?

Cheers,
Roman

Vinodlouis · March 13, 2017, 9:58am

Hi @roman.smirnov,

I tried processEngine.getFormService().getStartFormVariables(processDefinitionId).size() which returned 5 so after spending some time on it

VariableMapImpl m =  (VariableMapImpl)processEngine.getFormService().getStartFormVariables(processDefinitionId);
Set<Entry<String, Object>> mp= m.entrySet();
    	
for (Iterator iterator = mp.iterator(); iterator.hasNext();) {
    Entry<String, Object> entry = (Entry<String, Object>) iterator.next();
    System.out.println(entry.getKey() +"   "+entry.getValue());	
}

Here getKey() return me the key but getValue() returns null. I need the type of the variable like it says in rest API response docs as

{
  "amount": {
      "type": "Integer",
      "value": 5,
      "valueInfo": {}
  },
  "firstName": {
      "type": "String",
      "value": "Jonny",
      "valueInfo": {}
  }

}

Vinodlouis · March 13, 2017, 9:59am

Gson I just used for serialization earlier

roman.smirnov · March 13, 2017, 10:04am

That getValue() returns null is the expected behavior, since you are retrieving variables of a start form.

Could you please share the link of the docs you are mentioning?

Vinodlouis · March 13, 2017, 10:07am

@roman.smirnov Yes that I assumed must be the value of the variable like you said correctly. But while debugging the mp object it has values as {type:“Long”,value:null} So there must be a way to get that type like this docs says https://docs.camunda.org/manual/7.5/reference/rest/process-definition/get-form-variables/

Equivalent JAVA DOC https://docs.camunda.org/javadoc/camunda-bpm-platform/7.3/org/camunda/bpm/engine/FormService.html#getStartFormVariables(java.lang.String)

roman.smirnov · March 13, 2017, 11:24am

@Vinodlouis Could you please try to use VariablesMap#getValueTyped()? This would for example look like this

VariableMap m = formService.getStartFormVariables(processDefinition.getId());
Set<Entry<String, Object>> mp= m.entrySet();

for (Iterator iterator = mp.iterator(); iterator.hasNext();) {
  Entry<String, Object> entry = (Entry<String, Object>) iterator.next();
  TypedValue typedValue = m.getValueTyped(entry.getKey());
  System.out.println(entry.getKey() +"   "+typedValue.getType());
}

Cheers,
Roman

Vinodlouis · March 13, 2017, 11:40am

Thanks @roman.smirnov This meets my requirement. I guess this is missing in docs could be a good point to add there.