How to make a generic repository in Symfony 4

Question

I'm working with Symfony 4, I've a lot of repositories with common behaviour, so I want to avoid repeated code. I tried to define a parent repository class this way:

<?php
namespace App\Repository;

use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository;
use Symfony\Bridge\Doctrine\RegistryInterface;

class AppRepository extends ServiceEntityRepository {
    public function __construct(RegistryInterface $registry, $entityClass) {
        parent::__construct($registry, $entityClass);
    }

    // Common behaviour
}

So I would be able to define its children classes, for instance:

<?php
namespace App\Repository;

use App\Entity\Test;
use App\Repository\AppRepository;
use Symfony\Bridge\Doctrine\RegistryInterface;

class TestRepository extends AppRepository {
    public function __construct(RegistryInterface $registry) {
        parent::__construct($registry, Test::class);
    }
}

But I'm getting this error:

Cannot autowire service "App\Repository\AppRepository": argument "$entityClass" of method "__construct()" must have a type-hint or be given a value explicitly.

I tried setting type hinting like string, object but It didn't work.

Is there a way to define a generic repository?

Thanks in advance

Answer 1

One of the "gotchas" of autowire is that by default, autowire looks for all classes under src and attempts to make them into services. In some cases it ends up picking up classes such as your AppRepository which are not intended to be services and then fails when it tries to autowire them.

The most common solution is to explicitly exclude these classes:

# config/services.yaml
App\:
    resource: '../src/*'
    exclude: '../src/{DependencyInjection,Entity,Migrations,Tests,Kernel.php,Repository/AppRepository.php}'

Another approach that should work (not tested) is to make AppRepository abstract. Autowire will ignore abstract classes. Repositories are a bit tricky and having abstract classes extend non-abstract classes is somewhat unusual.