Database transactions implemented

data/classes/controller/FingerprintPostController.php

@@ -21,26 +21,35 @@ final class FingerprintPostController extends AbstractController
     {
         parent::handle();
 
+        $db = new MySqlDatabase();
         $json = json_decode($this->requestBody);
-        $fingerprint = new Fingerprint();
+        $fingerprint = new Fingerprint(null, $db);
 
         try {
             $fingerprint->setFingerprint($json->fingerprint);
             $fingerprint->setUserId($json->userId);
+
+            if (!$db->hasTransaction()) {
+                $db->startTransaction();
+            }
+
             $fingerprint->Save();
 
             $qrCode = new QrCode($fingerprint->getFingerprintId(), $fingerprint->getFingerprint());
             $qrCode->generate();
             $qrCode->save();
 
+            $db->commit();
+
             $this->response->setParameter('fingerprintId', $fingerprint->getFingerprintId());
         } catch (QrCodeException $e) {
-            $fingerprint->Delete();
+            $db->rollback();
 
             $this->response->setParameter('success', false);
             $this->response->setStatus(ServerStatus::INTERNAL_ERROR);
             $this->response->setMessage('An error occured during qr code creation!');
         } catch (Throwable $e) {
+            $db->rollback();
             $this->catchDatabaseException($e->getMessage(), $json);
         }
     }

data/classes/core/DatabaseInterface.php

@@ -53,6 +53,26 @@ interface DatabaseInterface
      */
     public function Count(string $table, array $conditions = []): int;
 
+    /*
+     * Returns if there's an open transaction.
+     */
+    public function hasTransaction(): bool;
+
+    /*
+     * Starts a transaction that can later be committed or rolled back.
+     */
+    public function startTransaction(): void;
+
+    /*
+     * Quits a current transaction without saving.
+     */
+    public function rollback(): void;
+
+    /*
+     * Saves and exits a current transaction.
+     */
+    public function commit(): void;
+
     /**
      * Returns the primary key from the last inserted row.
      */

data/classes/core/MySqlDatabase.php

@@ -2,12 +2,13 @@
 
 declare(strict_types=1);
 
-class MySqlDatabase implements DatabaseInterface
+final class MySqlDatabase implements DatabaseInterface
 {
 	private const CHARS_ALLOWED_IN_TABLE_NAMES = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890_-';
 
 	private ?PDO $connection;
 	private ?PDOStatement $cursor;
+    private bool $isTransactionOpen = false;
 
     public function __construct(
 		string $hostname = Setting::MYSQL_HOST,
@@ -236,6 +237,29 @@ class MySqlDatabase implements DatabaseInterface
         return (int)$result[0]['count(*)'];
     }
 
+    public function hasTransaction(): bool
+    {
+        return $this->isTransactionOpen;
+    }
+
+    public function startTransaction(): void
+    {
+        $this->connection->beginTransaction();
+        $this->isTransactionOpen = true;
+    }
+
+    public function rollback(): void
+    {
+        $this->connection->rollBack();
+        $this->isTransactionOpen = false;
+    }
+
+    public function commit(): void
+    {
+        $this->connection->commit();
+        $this->isTransactionOpen = false;
+    }
+
     /**
      * {@inheritDoc}
      */