Ordering embedded documents with Doctrine ODM - mongodb

Question

I’m trying to order my embed documents.
The field looks like this
/**
* #ODM\EmbedMany(targetDocument=Image::class, strategy="set")
* #ODM\Index(keys={"order"="asc"})
* #Groups({"offer:read"})
*/
protected $images = [];
The Image EmbeddedDocument
namespace App\Document\Embedded;
use App\Document\Traits\NameableTrait;
use App\Document\Traits\OrderableTrait;
use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
/**
* #ODM\EmbeddedDocument
*/
class Image
{
use NameableTrait;
use OrderableTrait;
…
}
And the orderable trait
namespace App\Document\Traits;
use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
use Symfony\Component\Serializer\Annotation\Groups;
trait OrderableTrait
{
/**
* #ODM\Field(type="int")
* #Groups({"offer:read"})
*
* #var int|null
*/
private $order;
public function getOrder(): int
{
return $this->order;
}
public function setOrder(int $order): void
{
$this->order = $order;
}
}
I updated the indexes with bin/console doctrine:mongodb:schema:update
However my Images are not ordered. Are the indexes the way to do it?

Answer 1

Index is not used for ordering documents in any way, they are telling the database to index the data so it can be searched through efficiently. In Doctrine's ORM there is an #OrderBy annotation but sadly it has not made its way to the ODM (yet). The solution would either be to support such thing natively in the ODM itself or you could use a custom collection for your embedded documents.
Here you will find documentation for custom collections and here's a link to my package that aims to kickstart your own implementations: https://github.com/malarzm/collections. To get what you need you will need your own collection class looking somehow like this:
class SortableCollection extends Malarzm\Collections\SortedCollection
{
public function compare($a, $b)
{
return $a->getOrder() <=> $b->getOrder();
}
}
and then plug it into your mapping:
/**
* #ODM\EmbedMany(targetDocument=Image::class, strategy="set", customCollection=SortableCollection::class)
* #ODM\Index(keys={"order"="asc"})
* #Groups({"offer:read"})
*/
protected $images = [];