Why custom condition is not containing parent entity?

Question

I'm using:

• Drupal 9.1.7
• Commerce 2.24

I'm trying to create my custom condition (based on https://docs.drupalcommerce.org/commerce2/developer-guide/core/conditions). However parent entity is always NULL. Seems like parent entity is only working when I specify commerce_order as entity_type only, but I need commerce_order_item. ParentEntityAwareInterface and ParentEntityAwareTrait are in use. Debugging show that:

  public function evaluate(EntityInterface $entity) {
    $this->assertEntity($entity);
    /** @var \Drupal\commerce_order\Entity\OrderItemInterface $order_item */
    $order_item = $entity;
    /** @var \Drupal\commerce_promotion\Entity\PromotionInterface $promotion */
    $promotion = $this->parentEntity;
    //$promotion is NULL
    // rest of the code
  }

$promotion is always null.

Annotation:

 * @CommerceCondition(
 *   id = "myproj_product_condition",
 *   label = @Translation("Product chooser"),
 *   category = @Translation("Product chooser"),
 *   entity_type = "commerce_order_item",
 *   parent_entity_type = "commerce_promotion",
 *   weight = 9,
 * )

Answer 1

The docs note this:

(If you want the Condition to apply to multiple parent entity types, you can leave this property unset; however, you will need to be careful in your evaluate() method implementation to check the type of the parent entity before accessing any of the parent entity's methods.)

So it seems the annotation would be:

 * @CommerceCondition(
 *   id = "myproj_product_condition",
 *   label = @Translation("Product chooser"),
 *   category = @Translation("Product chooser"),
 *   entity_type = "commerce_order_item",
 *   weight = 9,
 * )

and assert:

$promotion = $this->parentEntity;

if (check $promotion is a certain entity type) {
 ...
}

Clear your cache after updating the Annotation (and may have to re-create the Rule? unsure if it affects that). Beyond that it could be a bug in Drupal Commerce.