Add audit owner through parent model

Models that belong to an organization via a parent model (for example
project members via their project) implement AuditableThroughParent and
return the parent relation. The owner organization of their audits is
taken from the loaded parent if it matches the foreign key, otherwise it
is queried. The declaration is also used to backfill the owner of
existing audits.

app/Models/Concerns/CustomAuditable.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace App\Models\Concerns;
 
+use Illuminate\Database\Eloquent\Model;
 use Illuminate\Support\Facades\Config;
 use OwenIt\Auditing\Auditable;
 
@@ -27,6 +28,36 @@ trait CustomAuditable
      */
     public function getAuditOwnerOrganizationId(): ?string
     {
+        if ($this instanceof AuditableThroughParent) {
+            $relation = $this->getAuditParentRelation();
+            $parentId = $this->getAttributes()[$relation->getForeignKeyName()] ?? null;
+            if ($parentId === null) {
+                return null;
+            }
+
+            // Note: The loaded parent is only used if it still matches the foreign key and was loaded with the organization
+            $relationName = $relation->getRelationName();
+            if ($this->relationLoaded($relationName)) {
+                $parent = $this->getRelation($relationName);
+                if ($parent instanceof Model
+                    && $parent->getAttribute($relation->getOwnerKeyName()) === $parentId
+                    && array_key_exists('organization_id', $parent->getAttributes())) {
+                    /** @var string|null $organizationId */
+                    $organizationId = $parent->getAttributes()['organization_id'];
+
+                    return $organizationId;
+                }
+            }
+
+            /** @var string|null $organizationId */
+            $organizationId = $relation->getRelated()->newQuery()
+                ->toBase()
+                ->where($relation->getOwnerKeyName(), $parentId)
+                ->value('organization_id');
+
+            return $organizationId;
+        }
+
         return $this->getAttributes()['organization_id'] ?? null;
     }