Use custom Doctrine hydrator.

src/Bundle/ChillPersonBundle/Controller/SocialIssueApiController.php

@@ -3,11 +3,9 @@
 namespace Chill\PersonBundle\Controller;
 
 use Chill\MainBundle\CRUD\Controller\ApiController;
+use Chill\MainBundle\Doctrine\ORM\Hydration\FlatHierarchyEntityHydrator;
 use Chill\MainBundle\Pagination\PaginatorInterface;
-use Chill\PersonBundle\Entity\SocialWork\SocialIssue;
 use DateTimeImmutable;
-use Doctrine\ORM\QueryBuilder;
-use Generator;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 
@@ -26,23 +24,9 @@ class SocialIssueApiController extends ApiController
 
     protected function getQueryResult(string $action, Request $request, string $_format, int $totalItems, PaginatorInterface $paginator, $query)
     {
-        // Create a lazy generator to avoid performance issues.
-        $generator = $this->buildRecursively(
-                $query->getQuery()->getResult(),
-                static fn (SocialIssue $socialIssue): iterable => $socialIssue->getChildren()
-        );
-
-        // Sadly, we must convert the generator into an array...
-        // so we lose all the performance gain we could have by using an iterator.
-        $results = [];
-
-        // Reduce the generator into an array containing once each SocialIssue.
-        foreach ($generator as $socialIssue) {
-            // If the current item hasn't been seen yet, add it to the resultset.
-            $results += [$socialIssue->getId() => $socialIssue];
-        }
-
-        return $results;
+        // In order to work, this hydrator only works with
+        // entities having the field "children" set up.
+        return $query->getQuery()->getResult(FlatHierarchyEntityHydrator::LIST);
     }
 
     protected function onPostIndexBuildQuery(string $action, Request $request, string $_format, int $totalItems, PaginatorInterface $paginator, $query): ?Response
@@ -53,20 +37,4 @@ class SocialIssueApiController extends ApiController
 
         return null;
     }
-
-    /**
-     * @param iterable<int, SocialIssue> $iterable
-     * @param callable(SocialIssue): iterable<int, SocialIssue> $childrenAccessor
-     *
-     * @return Generator<int, SocialIssue>
-     */
-    private function buildRecursively(iterable $iterable, callable $childrenAccessor): Generator
-    {
-        foreach ($iterable as $item)
-        {
-            yield $item;
-
-            yield from $this->buildRecursively($childrenAccessor($item), $childrenAccessor);
-        }
-    }
 }