Fetching objects and adding a calculated field in Doctrine 2

Question

I'm making a section that shows a list of blogs and how many comments it has without loading any comment data. My Blog entity is as follows:

/**
 * @ORM\Entity
 * @ORM\Table(name="blogs")
 */
class Blog
{   
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

   // This field is aggregated. Not in DB table
    protected $totalComments = 0;

    /**
     * @ORM\Column(type="string")
     */
    protected $title;

     /**
     * @ORM\OneToMany(targetEntity="Comment", mappedBy="blog")
     */
    protected $comments;

    // More attributes

    public function __construct(){
        $this->comments = new ArrayCollection();
    }

    // Setters and Getters
}

and my Comment Entity:

class Comment
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @ORM\ManyToOne(targetEntity="Blog", inversedBy="comments")
     * @ORM\JoinColumn(name="blog_id", referencedColumnName="id")
     */
    protected $blog;

   // more attributes

    public function __construct(){     }

    // Setter and Getters
}

They have a oneToMany relationship. 1 Blog has N comments.

My next step is convert this query to the Doctrine2 World:

'SELECT b.*, COUNT( b.id ) AS totalComments FROM  `blogs` b LEFT JOIN comments c ON b.id = c.blog_id GROUP BY b.id'

That was an easy task:

function getLatestBlogs(){  
        $qb = $this->createQueryBuilder('b')
        ->select('b, c')
        ->addSelect('count(b.id) as totalComments')
        ->leftJoin('b.comments', 'c')
        ->groupBy('b.id');

        $result = $qb->getQuery()->getResult();

        foreach($qResult as $row){ //tweaking original result
            $row[0]->setTotalComments($row['totalComments']);
            $list[] = $row[0];
        }
        return $list;
    }

In the foreach loop is where I fix my fetched result because doctrine's getResult was returning an array of arrays like this:

// var_dump($result)
array (size=8)
  0 => 
    array(2) =>
      0 =>  
          object Blog
          'id' => int 330
          'title' => string 'title blog'
          // ... more attributes

      "totalComments" => int 5

  1 => ...
  );

Is there any fashion way that I'm missing ? I've really dig in to depth and couldn't find anything that fix this situation.

Answer 1

If you wanna just show them, just use

count($blog->getComments()) or blog.comments|length in template, or something similar.

Answer 2

In addition to previous answer

You can create method in repository like getBlogsWithJoins:

return $this->createQueryBuilder('b')
    ->select('b')
    ->join('b.comments')
    ->getQuery()
    ->getResult();

And then doctrine would load all the comments related to blog post in eager way.