EVENT_BEFORE_SAVE_ELEMENT Saving element loop in task/queue

Question

I'm calling EVENT_BEFORE_SAVE_ELEMENT to trigger a task that then updates the entry, but it's causing a loop?

The event is triggered when a specific entry type is saved:

Event::on(
  Elements::class,
  Elements::EVENT_BEFORE_SAVE_ELEMENT,
  function(Event $event) {
    $entry = $event->sender;
    if ($event->element instanceof \craft\elements\Entry) {
      $entry = $event->element;
      if (ElementHelper::isDraftOrRevision($entry)) {
        return;
      }
      if(($entry->sectionId == 18) && ($entry->typeId == 26)) {
        $signpostURL = $entry->getFieldValue('signpostUrl');
        if(($signpostURL) && ($signpostURL !== '')) {
          Craft::$app->queue->push(new BrowshotTask([
            'description' => 'Grabbing screenshot for '.$signpostURL,
            'url' => $signpostURL,
            'entryId' => $entry->id
          ]));
        }
      }
    }
  }
);

BrowshotTask then performs some API calls to a third-party service, gets a screenshot, saves an asset and saves the asset in the asset field of the entry.

But this triggers the event again and causes a loop:

$entry->setFieldValue('browsershotUrl', [$assetId]);
if(Craft::$app->elements->saveElement($entry)) {

Sometimes BrowshotTask can take 20 seconds due to the third-party service.. so I thought putting it in a task would be a great idea, but now it's causing me so many problems :(

Answer 1

The easiest solution for this would be either a special fieldvalue or a property in a behavior that you set in your job.

class MyJob extends BaseJob
{
    public function execute($queue): bool
    {
        // do some api calls here
        // ....
        $entry->isSavedViaApi = true;
        $entry->setFieldValue('browsershotUrl', [$assetId]);
        Craft::$app->elements->saveElement($entry)
        // ....
    }
}

and in your event, you can check against this property

Event::on(
  Elements::class,
  Elements::EVENT_BEFORE_SAVE_ELEMENT,
  function(Event $event) {
    $entry = $event->sender;
    if ($event->element instanceof \craft\elements\Entry) {
      $entry = $event->element;
      if (ElementHelper::isDraftOrRevision($entry)) {
        return;
      }

      if(($entry->sectionId == 18) && ($entry->typeId == 26)) {

        // make sure to check the section first, because otherwise the entry
        // may not have this property of field
        if($entry->isSavedViaApi === true){
            return;
        }
        //


        $signpostURL = $entry->getFieldValue('signpostUrl');
        if(($signpostURL) && ($signpostURL !== '')) {
          Craft::$app->queue->push(new BrowshotTask([
            'description' => 'Grabbing screenshot for '.$signpostURL,
            'url' => $signpostURL,
            'entryId' => $entry->id
          ]));
        }
      }
    }
  }
);

If you want to use a behavior instead of a field value for this

use yii\base\Behavior;

class MyBehavior extends Behavior
{
    public $isSavedViaApi = false;
}

and in your main module file

use craft\elements\Entry;
use craft\events\DefineBehaviorsEvent;

Event::on(
    Entry::class,
    Entry::EVENT_DEFINE_BEHAVIORS,
    static function(DefineBehaviorsEvent $event) {
        //so every element gets a isSubscribed attached
        $event->behaviors[] = MyBehavior::class;
    }
);