[Feature Request] Provide a typed result API

[knegyesi]

Is your feature request related to a problem? Please describe.

I would like to retrieve the result of a workflow run. The workflow method has a return type but this is not taken into account because getResult only exists on the untyped stub as the typed stub is a proxy class to the workflow and calls workflow class methods but the untyped stub doesn't have type info.

Describe the solution you'd like

There should be a higher level API than WorkflowRunInterface::getResult which can infer the type automatically from the return type of the workflow method. Since the return workflow method must be a supertype of Generator this might need the ability to handle composite types, there are multiple type libraries for example symfony/type-info although I have simply done

    $workflowReturnType = $this->temporalFactories
      ->getWorkflowStub($workflowClass)
      ->getHandlerReflection()
      ->getReturnType();
    if ($workflowReturnType instanceof \ReflectionUnionType &&
      ($types = array_diff(array_map('strval', $workflowReturnType->getTypes()), ['Generator']))) {
      return reset($types);
    }

in my workaround to the problem.

[xepozz]

Hi @knegyesi
Could you also provide an example of your workflow class?
Are there any disadvantages? BC? Anything else? Btw, PR is welcome.
I had tried to implement auto-type providing with https://github.com/php-type-language.
As far as I remember @SerafimArts is planning to release 2.0 version soon, so it could be used here instead of current "Marshaller".

[roxblnfk]

Try the #[ReturnType] attribute on the workflow method

[knegyesi]

Well, my current example is a bit more complicated than it could be because I am returning a third party object but here it is:

#[WorkflowInterface]
class DrupalBatchWorkflow {

  #[WorkflowMethod('drupal_batch')]
  public function run(int $batchId): RedirectResponseWrapper|\Generator {

where RedirectResponseWrapper is

readonly class RedirectResponseWrapper implements ResultInterface {

  public function __construct(
    #[Marshal(type: RedirectResponseType::class)]
    public RedirectResponse $response,
  ) {}

I wrote a RedirectResponseType and found no other way to wire it in but that's another issue.

I tried adding #[ReturnType(RedirectResponseWrapper::class)] on the method but ->newUntypedRunningWorkflowStub($workflowId)->getResult() still returns a stdClass.

[roxblnfk]

https://php.temporal.io/classes/Temporal-Workflow-WorkflowRunInterface.html#method_getResult
try to specify result type in the first getResult() parameter

[knegyesi]

But that's exactly what I wanted to avoid, I wanted a generic getResult() which grabs the result type from the workflow, it belongs to the workflow, not the query.

The Drupal integration does it, it's just a bit complex. https://git.drupalcode.org/project/temporal/-/blob/2.x/src/ResultHelper.php?ref_type=heads#L56

[SerafimArts]

I had tried to implement auto-type providing with @php-type-language.
As far as I remember @SerafimArts is planning to release 2.0 version soon, so it could be used here instead of current "Marshaller".

@xepozz I'm currently working on the phplrt 4 release (https://github.com/phplrt/phplrt/releases) and plan to primarily update TypeLang to this version. Currently, this is a blocker for the release of TypeLang's 2.0 version.

Regarding the mapper, as I already wrote on Reddit, it requires a comprehensive core refactoring and a lot of work, so it's not guaranteed to be released with version 2.0. I would recommend not waiting for its release, but using either the current build or more mature solutions, such as JMS Serializer.

[knegyesi]

Sorry, there are two issues here:

1. How to get to the workflow class from the workflow id? I just had an idea which I could submit even as a PR: put the workflow class in the memo on start.
2. How to determine the return type. Perhaps automated is too much then yet and the return type annotation could be used?

As for the first, approximately:

        $workflowStub = WorkflowStubConverter::fromWorkflow($workflow);
        $options = $workflowStub->getOptions() ?? WorkflowOptions::new();

        $returnType = null;
        if ($workflow instanceof WorkflowProxy) {
            $method = $workflow->getHandlerReflection();
            $options = $options
              ->withMemo(
                ['__PHP_CLASS' => $method->class] +
                (array) $options->memo()
              );

in WorkflowClient::start