How to pass the input variables of User Task to the appServices ??

[shashank-yelluri-dn]

Hello @ralphhanna,
Good Afternoon !!

We have a requirement where we define some input variables to the user task and we want to pass the input variables to the appServices defined method. Today, i could see from the provided examples in the bpmn-web only passing the this, which is context. Is there anyway that we can pass inputs ?

Thank You in advance

[ralphhanna]

When Calling AppServices from Trigger Script

The example you provided is an end trigger for a UserTask
you can pass any parameters you like as well as the entire data object is available
this in the example above refers to the current item
Your calling script should be like this:

 appServices.myMethod1({var1:50,var2:'some text'},this);

therefore, inside your method, you can:

class AppServices 
// ... more here 

async myMethod1(input,item) {
   const dataVar1=context.data.var1;
}

When Calling Service Tasks

The proper syntax is as follows:

Input/Output Parameters are set as follows:

class AppServices 
// ... more here 
    async echo(input, context) {
        console.log('service echo - input', input);
        context.item.data['echo']=input;
        return input;
    }

When you inspect the passed values

[shashank-yelluri-dn]

Great !!
Thank You for the quick response. Is there any way that we can throw the error from this "end" execution listener ? I want to validate the data provided for the user task and do not let the user invoke the task.

@ralphhanna

[ralphhanna]

Yes, Use Validate trigger https://bpmnserver.github.io/docs/execution/?h=validation#validation-scripts

[shashank-yelluri-dn]

@ralphhanna - I've tried with the return {bpmnError:'error code'}; & it is closing the workflow. But the response of the engine invoke is still not giving any response relevant to the error code provided in the end execution listener.

So we cannot use this, as it is exiting the workflow. We are looking for something, which blocks in invoking the task with a error message (provided in the bpmn file) & give us in the response of invoke, so that we can show it on our UI. Once that validation is success, then we need to invoke & move the token further.

Thank You in advance

[ralphhanna]

Please try validate event not end event

Here is my log:

Node(Buy|task_Buy).doEvent: executing script for event:transformInput ended
 Node(Buy|task_Buy).doEvent: executing script for event:validate newStatus:wait
 --executing script for event:validate
{
  caseId: 5068,
  starterUserId: 'system',
  startDate: null,
  returnTo: 'undefined',
  needsRepairs: '',
  needsCleaning: 'No'
}
 Node(Buy|task_Buy).doEvent: executing script for event:validate ended
Exception: stack Error: Validation failed with error:Invalid values
    at Logger.error (C:\bp\dev\server\dist\common\Logger.js:116:15)
    at Execution.error (C:\bp\dev\server\dist\engine\Execution.js:617:21)
    at C:\bp\dev\server\dist\elements\Node.js:46:46
    at Array.forEach (<anonymous>)
    at UserTask.<anonymous> (C:\bp\dev\server\dist\elements\Node.js:42:22)
    at Generator.next (<anonymous>)
    at fulfilled (C:\bp\dev\server\dist\elements\Node.js:5:58)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
 ...unlocking ..f2b9210a-47c7-4966-a201-194f8e2a2a15
 remove done for  1 docs in wf_locks
POST /invokeItem 200 144.989 ms - 57
needsRepairs

validate - stops invoke command from proceeding.

[shashank-yelluri-dn]

But validate is not there in Camunda version 7 😟

[shashank-yelluri-dn]

Also, how can I get the text of “invalid value” ? I could see it in the logs, but does this value be there in the response of invoke function ? Else how can we fetch the error coded provided in the file.

[shashank-yelluri-dn]

Even the camunda 8 is not having the option of validate. I'm building the model using camunda modeller

[ralphhanna]

I don't know anything about Camunda, use bpmn-web editor (under Task listener) or just edit the xml file:

    <bpmn:userTask id="task_Buy" name="Buy" camunda:assignee="$(this.data.starterUserId)" camunda:candidateUsers="User1,User2" camunda:candidateGroups="Employee,Manager" camunda:dueDate="$this.dueDate" camunda:followUpDate="2023-10-31" camunda:priority="5">
      <bpmn:documentation>A User Task</bpmn:documentation>
      <bpmn:extensionElements>
        <camunda:formData>
          <camunda:formField id="needsRepairs" label="Repairs Required?" type="boolean" defaultValue="No" />
          <camunda:formField id="needsCleaning" label="Cleaning Required?" type="boolean" defaultValue="No" />
        </camunda:formData>

        <camunda:taskListener event="validate">
          <camunda:script scriptFormat="JavaScript">

console.log(data);
if (data.needsRepairs==="")
return {error: 'Invalid values'}

</camunda:script>
        </camunda:taskListener>

      </bpmn:extensionElements>
      <bpmn:incoming>flow_start_buy</bpmn:incoming>
      <bpmn:outgoing>flow_buy_gw</bpmn:outgoing>
    </bpmn:userTask>

[shashank-yelluri-dn]

Ok sure.

[ralphhanna]

The input value is in the input stream, either in item.input or item.data during validate, but will not be saved.