Save element parameters in its own database table (dont use JSON)

This makes it easier to query for specific parameters.

src/Entity/Parameters/ParametersTrait.php

@@ -0,0 +1,63 @@
+<?php
+/**
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ * Copyright (C) 2019 - 2020 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\Entity\Parameters;
+
+
+use App\Entity\Parameters\AbstractParameter;
+use Doctrine\Common\Collections\Collection;
+use Symfony\Component\Validator\Constraints as Assert;
+
+trait ParametersTrait
+{
+    /**
+     * Mapping done in subclasses
+     * @var AbstractParameter[]|Collection
+     * @Assert\Valid()
+     */
+    protected $parameters;
+
+    /**
+     * Return all associated specifications
+     * @return AbstractParameter[]|Collection
+     */
+    public function getParameters(): Collection
+    {
+        return $this->parameters;
+    }
+
+    /**
+     * Add a new parameter information.
+     * @param  AbstractParameter  $parameter
+     * @return $this
+     */
+    public function addParameter(AbstractParameter $parameter): self
+    {
+        $parameter->setElement($this);
+        $this->parameters->add($parameter);
+        return $this;
+    }
+
+    public function removeParameter(AbstractParameter $parameter): self
+    {
+        $this->parameters->removeElement($parameter);
+        return $this;
+    }
+}