diff --git a/src/Entity/Attachments/Attachment.php b/src/Entity/Attachments/Attachment.php
index 37a6f4fc..caf9559e 100644
--- a/src/Entity/Attachments/Attachment.php
+++ b/src/Entity/Attachments/Attachment.php
@@ -44,6 +44,7 @@ declare(strict_types=1);
 namespace App\Entity\Attachments;
 
 use App\Entity\Base\NamedDBElement;
+use App\Entity\Parts\Category;
 use App\Validator\Constraints\Selectable;
 use Doctrine\ORM\Mapping as ORM;
 
@@ -74,7 +75,7 @@ abstract class Attachment extends NamedDBElement
      * It will be used to determine if a attachment is a picture and therefore will be shown to user as preview.
      */
     public const PICTURE_EXTS = ['apng', 'bmp', 'gif', 'ico', 'cur', 'jpg', 'jpeg', 'jfif', 'pjpeg', 'pjp', 'png',
-                            'svg', 'webp'];
+        'svg', 'webp'];
 
     /**
      * A list of extensions that will be treated as a 3D Model that can be shown to user directly in Part-DB.
@@ -120,6 +121,19 @@ abstract class Attachment extends NamedDBElement
      */
     protected $attachment_type;
 
+    /**
+     * @var string The class of the element that can be passed to this attachment. Must be overriden in subclasses.
+     */
+    public const ALLOWED_ELEMENT_CLASS = '';
+
+    public function __construct()
+    {
+        //parent::__construct();
+        if (static::ALLOWED_ELEMENT_CLASS === '') {
+            throw new \LogicException('An *Attachment class must override the ALLOWED_ELEMENT_CLASS const!');
+        }
+    }
+
     /***********************************************************
      * Various function
      ***********************************************************/
@@ -367,7 +381,19 @@ abstract class Attachment extends NamedDBElement
         return $this;
     }
 
-    abstract public function setElement(AttachmentContainingDBElement $element) : Attachment;
+    public function setElement(AttachmentContainingDBElement $element) : Attachment
+    {
+        if (!is_a($element,static::ALLOWED_ELEMENT_CLASS)) {
+            throw new \InvalidArgumentException(sprintf(
+                'The element associated with a %s must be a %s!',
+                get_class($this),
+                static::ALLOWED_ELEMENT_CLASS
+            ));
+        }
+
+        $this->element = $element;
+        return $this;
+    }
 
     /**
      * @param string $path
diff --git a/src/Entity/Attachments/AttachmentTypeAttachment.php b/src/Entity/Attachments/AttachmentTypeAttachment.php
index 892756f1..b8c0577a 100644
--- a/src/Entity/Attachments/AttachmentTypeAttachment.php
+++ b/src/Entity/Attachments/AttachmentTypeAttachment.php
@@ -40,13 +40,5 @@ class AttachmentTypeAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof AttachmentType) {
-            throw new \InvalidArgumentException('The element associated with a AttachmentTypeAttachment must be an AttachmentType!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
+    public const ALLOWED_ELEMENT_CLASS =  AttachmentType::class;
 }
\ No newline at end of file
diff --git a/src/Entity/Attachments/CategoryAttachment.php b/src/Entity/Attachments/CategoryAttachment.php
index 0ff0cbfc..bd7ed4cc 100644
--- a/src/Entity/Attachments/CategoryAttachment.php
+++ b/src/Entity/Attachments/CategoryAttachment.php
@@ -42,13 +42,5 @@ class CategoryAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof Category) {
-            throw new \InvalidArgumentException('The element associated with a CategoryAttachment must be a Category!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
+    public const ALLOWED_ELEMENT_CLASS = Category::class;
 }
\ No newline at end of file
diff --git a/src/Entity/Attachments/CurrencyAttachment.php b/src/Entity/Attachments/CurrencyAttachment.php
index dfb70b0d..af90fe88 100644
--- a/src/Entity/Attachments/CurrencyAttachment.php
+++ b/src/Entity/Attachments/CurrencyAttachment.php
@@ -46,13 +46,5 @@ class CurrencyAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof Currency) {
-            throw new \InvalidArgumentException('The element associated with a CurrencyAttachment must be a Currency!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
+    public const ALLOWED_ELEMENT_CLASS = Currency::class;
 }
\ No newline at end of file
diff --git a/src/Entity/Attachments/DeviceAttachment.php b/src/Entity/Attachments/DeviceAttachment.php
index 9e28523a..670e6a17 100644
--- a/src/Entity/Attachments/DeviceAttachment.php
+++ b/src/Entity/Attachments/DeviceAttachment.php
@@ -33,7 +33,6 @@ use Doctrine\ORM\Mapping as ORM;
  */
 class DeviceAttachment extends Attachment
 {
-
     /**
      * @var Device The element this attachment is associated with.
      * @ORM\ManyToOne(targetEntity="App\Entity\Devices\Device", inversedBy="attachments")
@@ -41,13 +40,5 @@ class DeviceAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof Device) {
-            throw new \InvalidArgumentException('The element associated with a PartAttachment must be a Device!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
+    public const ALLOWED_ELEMENT_CLASS = Device::class;
 }
\ No newline at end of file
diff --git a/src/Entity/Attachments/FootprintAttachment.php b/src/Entity/Attachments/FootprintAttachment.php
index 21aecc3f..9251b7b2 100644
--- a/src/Entity/Attachments/FootprintAttachment.php
+++ b/src/Entity/Attachments/FootprintAttachment.php
@@ -42,13 +42,5 @@ class FootprintAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof Footprint) {
-            throw new \InvalidArgumentException('The element associated with a FootprintAttachment must be a Footprint!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
+    public const ALLOWED_ELEMENT_CLASS = Footprint::class;
 }
\ No newline at end of file
diff --git a/src/Entity/Attachments/GroupAttachment.php b/src/Entity/Attachments/GroupAttachment.php
index 0951ce9b..d1300172 100644
--- a/src/Entity/Attachments/GroupAttachment.php
+++ b/src/Entity/Attachments/GroupAttachment.php
@@ -48,13 +48,5 @@ class GroupAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof Group) {
-            throw new \InvalidArgumentException('The element associated with a UserAttachment must be a User!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
-}
\ No newline at end of file
+    public const ALLOWED_ELEMENT_CLASS = Group::class;
+}
diff --git a/src/Entity/Attachments/ManufacturerAttachment.php b/src/Entity/Attachments/ManufacturerAttachment.php
index d6829047..a9827fa1 100644
--- a/src/Entity/Attachments/ManufacturerAttachment.php
+++ b/src/Entity/Attachments/ManufacturerAttachment.php
@@ -42,13 +42,5 @@ class ManufacturerAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof Manufacturer) {
-            throw new \InvalidArgumentException('The element associated with a ManufacturerAttachment must be a Manufacturer!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
+    public const ALLOWED_ELEMENT_CLASS = Manufacturer::class;
 }
\ No newline at end of file
diff --git a/src/Entity/Attachments/MeasurementUnitAttachment.php b/src/Entity/Attachments/MeasurementUnitAttachment.php
index a47bd0a1..1f873ac6 100644
--- a/src/Entity/Attachments/MeasurementUnitAttachment.php
+++ b/src/Entity/Attachments/MeasurementUnitAttachment.php
@@ -43,13 +43,5 @@ class MeasurementUnitAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof MeasurementUnit) {
-            throw new \InvalidArgumentException('The element associated with a MeasurementUnitAttachmentAttachment must be a MeasurementUnit!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
+    public const ALLOWED_ELEMENT_CLASS = MeasurementUnit::class;
 }
\ No newline at end of file
diff --git a/src/Entity/Attachments/PartAttachment.php b/src/Entity/Attachments/PartAttachment.php
index e1c5f5c9..986dddbc 100644
--- a/src/Entity/Attachments/PartAttachment.php
+++ b/src/Entity/Attachments/PartAttachment.php
@@ -40,13 +40,5 @@ class PartAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof Part) {
-            throw new \InvalidArgumentException('The element associated with a PartAttachment must be a Part!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
+    public const ALLOWED_ELEMENT_CLASS = Part::class;
 }
\ No newline at end of file
diff --git a/src/Entity/Attachments/StorelocationAttachment.php b/src/Entity/Attachments/StorelocationAttachment.php
index 6819d803..ee27f5a7 100644
--- a/src/Entity/Attachments/StorelocationAttachment.php
+++ b/src/Entity/Attachments/StorelocationAttachment.php
@@ -28,6 +28,7 @@ use App\Entity\Parts\MeasurementUnit;
 use App\Entity\Parts\Part;
 use App\Entity\Parts\Storelocation;
 use Doctrine\ORM\Mapping as ORM;
+use Symfony\Component\HttpKernel\HttpCache\Store;
 
 /**
  * A attachment attached to a measurement unit element.
@@ -44,13 +45,5 @@ class StorelocationAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof Storelocation) {
-            throw new \InvalidArgumentException('The element associated with a StorelocationAttachment must be a Storelocation!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
+    public const ALLOWED_ELEMENT_CLASS = Storelocation::class;
 }
\ No newline at end of file
diff --git a/src/Entity/Attachments/SupplierAttachment.php b/src/Entity/Attachments/SupplierAttachment.php
index 616dcff5..5be36d8b 100644
--- a/src/Entity/Attachments/SupplierAttachment.php
+++ b/src/Entity/Attachments/SupplierAttachment.php
@@ -45,13 +45,5 @@ class SupplierAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof Supplier) {
-            throw new \InvalidArgumentException('The element associated with a SupplierAttachment must be a Supplier!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
+    public const ALLOWED_ELEMENT_CLASS = Supplier::class;
 }
\ No newline at end of file
diff --git a/src/Entity/Attachments/UserAttachment.php b/src/Entity/Attachments/UserAttachment.php
index d2dfba64..76bbe08b 100644
--- a/src/Entity/Attachments/UserAttachment.php
+++ b/src/Entity/Attachments/UserAttachment.php
@@ -47,13 +47,5 @@ class UserAttachment extends Attachment
      */
     protected $element;
 
-    public function setElement(AttachmentContainingDBElement $element): Attachment
-    {
-        if (!$element instanceof User) {
-            throw new \InvalidArgumentException('The element associated with a UserAttachment must be a User!');
-        }
-
-        $this->element = $element;
-        return $this;
-    }
+    public const ALLOWED_ELEMENT_CLASS = User::class;
 }
\ No newline at end of file
diff --git a/tests/Entity/AttachmentTest.php b/tests/Entity/Attachments/AttachmentTest.php
similarity index 62%
rename from tests/Entity/AttachmentTest.php
rename to tests/Entity/Attachments/AttachmentTest.php
index 6335c19d..1a908758 100644
--- a/tests/Entity/AttachmentTest.php
+++ b/tests/Entity/Attachments/AttachmentTest.php
@@ -20,16 +20,113 @@
  *
  */
 
-namespace App\Tests\Entity;
+namespace App\Tests\Entity\Attachments;
 
 
 use App\Entity\Attachments\Attachment;
+use App\Entity\Attachments\AttachmentType;
+use App\Entity\Attachments\AttachmentTypeAttachment;
+use App\Entity\Attachments\CategoryAttachment;
+use App\Entity\Attachments\CurrencyAttachment;
+use App\Entity\Attachments\DeviceAttachment;
+use App\Entity\Attachments\FootprintAttachment;
+use App\Entity\Attachments\GroupAttachment;
+use App\Entity\Attachments\ManufacturerAttachment;
+use App\Entity\Attachments\MeasurementUnitAttachment;
 use App\Entity\Attachments\PartAttachment;
+use App\Entity\Attachments\StorelocationAttachment;
+use App\Entity\Attachments\SupplierAttachment;
+use App\Entity\Attachments\UserAttachment;
+use App\Entity\Devices\Device;
+use App\Entity\Parts\Category;
+use App\Entity\Parts\Footprint;
+use App\Entity\Parts\Manufacturer;
+use App\Entity\Parts\MeasurementUnit;
+use App\Entity\Parts\Part;
+use App\Entity\Parts\Storelocation;
+use App\Entity\Parts\Supplier;
+use App\Entity\PriceInformations\Currency;
+use App\Entity\UserSystem\Group;
+use App\Entity\UserSystem\User;
 use PHPUnit\Framework\TestCase;
 use ReflectionClass;
+use Symfony\Component\HttpKernel\HttpCache\Store;
 
 class AttachmentTest extends TestCase
 {
+    public function testEmptyState() : void
+    {
+        $attachment = new PartAttachment();
+
+        $this->assertNull($attachment->getAttachmentType());
+        $this->assertFalse($attachment->isPicture());
+        $this->assertFalse($attachment->isExternal());
+        $this->assertFalse($attachment->isSecure());
+        $this->assertFalse($attachment->isBuiltIn());
+        $this->assertFalse($attachment->is3DModel());
+        $this->assertFalse($attachment->getShowInTable());
+        $this->assertEmpty($attachment->getPath());
+        $this->assertEmpty($attachment->getName());
+        $this->assertEmpty($attachment->getURL());
+        $this->assertEmpty($attachment->getExtension());
+        $this->assertNull($attachment->getElement());
+        $this->assertEmpty($attachment->getFilename());
+    }
+
+    public function subClassesDataProvider() : array
+    {
+        return [
+            [AttachmentTypeAttachment::class, AttachmentType::class],
+            [CategoryAttachment::class, Category::class],
+            [CurrencyAttachment::class, Currency::class],
+            [DeviceAttachment::class, Device::class],
+            [FootprintAttachment::class, Footprint::class],
+            [GroupAttachment::class, Group::class],
+            [ManufacturerAttachment::class, Manufacturer::class],
+            [MeasurementUnitAttachment::class, MeasurementUnit::class],
+            [PartAttachment::class, Part::class],
+            [StorelocationAttachment::class, Storelocation::class],
+            [SupplierAttachment::class, Supplier::class],
+            [UserAttachment::class, User::class]
+        ];
+    }
+
+    /**
+     * @dataProvider subClassesDataProvider
+     * @param string $attachment_class
+     * @param string $allowed_class
+     */
+    public function testSetElement(string $attachment_class, string $allowed_class) : void
+    {
+        /** @var Attachment $attachment */
+        $attachment = new $attachment_class();
+        $element = new $allowed_class();
+
+        //This must not throw an exception
+        $attachment->setElement($element);
+        $this->assertEquals($element, $attachment->getElement());
+    }
+
+    /**
+     * Test that all attachment subclasses like PartAttachment or similar returns an exception, when an not allowed
+     * element is passed.
+     * @dataProvider subClassesDataProvider
+     * @depends  testSetElement
+     */
+    public function testSetElementExceptionOnSubClasses(string $attachment_class, string $allowed_class) : void
+    {
+        $this->expectException(\InvalidArgumentException::class);
+
+        /** @var Attachment $attachment */
+        $attachment = new $attachment_class();
+        if ($allowed_class !== Device::class) {
+            $element = new Device();
+        } else {
+            $element = new Category();
+        }
+        $attachment->setElement($element);
+    }
+
     public function externalDataProvider()
     {
         return [