not working

src/Entity/MerParaDT.php

@@ -8,8 +8,6 @@ use Doctrine\ORM\Mapping as ORM;
 #[ORM\Entity(repositoryClass: MerParaDTRepository::class)]
 class MerParaDT extends MerService
 {
-    use MerDT;
-
 //    #[ORM\Id]
 //    #[ORM\GeneratedValue]
 //    #[ORM\Column(type: 'integer')]
@@ -18,6 +16,10 @@ class MerParaDT extends MerService
     #[ORM\Column(type: 'string', length: 255)]
     private $api_key;
 
+    #[ORM\OneToOne(targetEntity: MerDT::class, cascade: ['persist'])]
+    #[ORM\JoinColumn(nullable: false)]
+    private MerDT $platform;
+
 //    public function getId(): ?int
 //    {
 //        return $this->id;
@@ -34,4 +36,16 @@ class MerParaDT extends MerService
 
         return $this;
     }
+
+    public function getPlatform(): ?MerDT
+    {
+        return $this->platform;
+    }
+
+    public function setPlatform(?MerDT $platform): self
+    {
+        $this->platform = $platform;
+
+        return $this;
+    }
 }