[Course comment] add validationConstraint NotNull and NotBlank on comment content, to avoid sql error

src/Bundle/ChillPersonBundle/Entity/AccompanyingPeriod/Comment.php

@@ -19,6 +19,7 @@ use DateTimeInterface;
 use Doctrine\ORM\Mapping as ORM;
 use Symfony\Component\Serializer\Annotation\DiscriminatorMap;
 use Symfony\Component\Serializer\Annotation\Groups;
+use Symfony\Component\Validator\Constraints as Assert;
 
 /**
  * @ORM\Entity
@@ -40,6 +41,8 @@ class Comment implements TrackCreationInterface, TrackUpdateInterface
     /**
      * @ORM\Column(type="text")
      * @Groups({"read", "write"})
+     * @Assert\NotBlank()
+     * @Assert\NotNull()
      */
     private $content;