Fixed import errors and reuse existing datastructrues from DB while importing complex data

Also now imports should not create duplicate instances of the same data elements. This fixes issue #101.

src/Serializer/StructuralElementDenormalizer.php

@@ -0,0 +1,92 @@
+<?php
+/*
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ *  Copyright (C) 2019 - 2023 Jan Böhmer (https://github.com/jbtronics)
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published
+ *  by the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+namespace App\Serializer;
+
+use App\Entity\Base\AbstractStructuralDBElement;
+use App\Repository\StructuralDBElementRepository;
+use Doctrine\ORM\EntityManagerInterface;
+use Symfony\Component\Serializer\Normalizer\CacheableSupportsMethodInterface;
+use Symfony\Component\Serializer\Normalizer\ContextAwareDenormalizerInterface;
+use Symfony\Component\Serializer\Normalizer\DenormalizerInterface;
+use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
+use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
+
+class StructuralElementDenormalizer implements ContextAwareDenormalizerInterface, CacheableSupportsMethodInterface
+{
+
+    private NormalizerInterface $normalizer;
+    private EntityManagerInterface $entityManager;
+
+    private array $object_cache = [];
+
+    public function __construct(ObjectNormalizer $normalizer, EntityManagerInterface $entityManager)
+    {
+        $this->normalizer = $normalizer;
+        $this->entityManager = $entityManager;
+    }
+
+    public function supportsDenormalization($data, string $type, string $format = null, array $context = [])
+    {
+        return is_array($data)
+            && is_subclass_of($type, AbstractStructuralDBElement::class)
+            //Only denormalize if we are doing an file import operation
+            && in_array('import', $context['groups'] ?? []);
+    }
+
+    public function denormalize($data, string $type, string $format = null, array $context = [])
+    {
+        /** @var AbstractStructuralDBElement $deserialized_entity */
+        $deserialized_entity = $this->normalizer->denormalize($data, $type, $format, $context);
+
+        //Check if we already have the entity in the database (via path)
+        /** @var StructuralDBElementRepository $repo */
+        $repo = $this->entityManager->getRepository($type);
+
+        $path = $deserialized_entity->getFullPath(AbstractStructuralDBElement::PATH_DELIMITER_ARROW);
+        $db_elements = $repo->getEntityByPath($path, AbstractStructuralDBElement::PATH_DELIMITER_ARROW);
+        if ($db_elements) {
+            //We already have the entity in the database, so we can return it
+            return end($db_elements);
+        }
+
+
+        //Check if we have created the entity in this request before (so we don't create multiple entities for the same path)
+        //Entities get saved in the cache by type and path
+        //We use a different cache for this then the objects created by a string value (saved in repo). However that should not be a problem
+        //unless the user data has mixed structure between json data and a string path
+        if (isset($this->object_cache[$type][$path])) {
+            return $this->object_cache[$type][$path];
+        }
+
+        //Save the entity in the cache
+        $this->object_cache[$type][$path] = $deserialized_entity;
+
+        //We don't have the entity in the database, so we have to persist it
+        $this->entityManager->persist($deserialized_entity);
+
+        return $deserialized_entity;
+    }
+
+    public function hasCacheableSupportsMethod(): bool
+    {
+        return false;
+    }
+}