Symfony doctrine lazy load properties - php

Question

I have an entity that stores large files as blobs to the DB.
I would now like to get Symfony to never ever load these blobs unless I specifically request them via the appropriate getter.
In essence I want the same idea as lazy-loading relationships but for a string property.
What I have tried so far is to put all my other properties that hold the file meta data into a trait and then apply that trait to two entities.
namespace App\Entity\Traits;
use Doctrine\ORM\Mapping as ORM;
trait DocumentMetaData
{
/**
* #var int|null
*
* #ORM\Id
* #ORM\Column(type="integer")
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #var \DateTime|null
*
* #ORM\Column(type="datetime")
*/
private $date_uploaded;
}
One entity has nothing to it but the trait...
namespace App\Entity;
use App\Entity\Traits\DocumentMetaData;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Table(name="documents")
* #ORM\Entity()
*/
class Document
{
use DocumentMetaData;
}
...the other has the added blob property:
namespace App\Entity;
use App\Entity\Traits\DocumentMetaData;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Table(name="documents")
* #ORM\Entity()
*/
class DocumentFile
{
use DocumentMetaData;
/**
* #var string|null
*
* #ORM\Column(type="blob")
*/
private $blob;
}
Now, if I don't want the blob to be loaded, for example for a listing of files, I simply use the entity that doesn't have the blob.
This approach sort of works but causes issues as I need to point both entities at the same table (see the class level ORM annotations).
Specifically, it makes doctrine freak out when running migrations:
The table with name 'myapp.documents' already exists.
That makes perfect sense and really I'm hoping that someone can point me to a nicer solution.
How can I tell doctrine not to load the blob unless its explicitly asked for?

Answer 1

So as per the comments on my question - the way to do this so that migrations do not break is to leverage doctrine's ability to lazy load relationships between tables.
Basically I had to go and create a new entity that only holds my giant blobs and then establish a one to one relationship between the original entity and the blob entity.
I then set that relationship to load EXTRA_LAZY and as a result I can now control when precisely the blobs of giant data should be loaded.
I don't think this is ideal in terms of normalising the DB design but it works a lot better than anything else so happy with that.