Doctrine is Cool

Comment.php

<?php

class Comment 
{
  private $message;
  private $author;
  private $createdAt;
  
  public function __construct(string $message, User $author)
  {
    $this->message = $message;
    $this->author = $author;
    $this->createdAt = new DateTime();
  }
  
}

Post.php

<?php

class Post
{
  private $id;
  private $title;
  private $content;
  private $comments;
  
  public function __construct(string $title, string $content)
  {
    $this->title = $title;
    $this->content = $content;
    $this->createdAt = new DateTime();
    $this->comments = new ArrayCollection();
  }
  
  public function addComment(string $comment, User $author)
  {
    $this->comments->add(new Comment($comment, $author));
  }
}

PostsController.php

<?php

class PostsController extends Controller
{
  // ..
  
  /**
   * @Config\Method("POST")
   * @Config\Route('/posts/{id}/comments')
   */
  public function addCommentAction(Request $request, Post $post)
  {
    $post->addComment($request->get('message'), $this->getUser());
    $this->flushChanges();
    
    return new Response(null, 201);
  }
  
  // ..
}