Doctrine get all entities from collection - symfony

Question

I don't know if what I am trying is really possible. So I thought to ask it to you guys.
What I am trying to do:
get a set of companies
get all the users associated with the given companies
In code:
$companyIds = array(1,2,3);
$companies = $this->em->getRepository('AppBundle:Company')->findById($companyIds);
dump($companies->getUsers()); // this will not work, but I like it to work
Where they are associated as follows:
class User implements AdvancedUserInterface, \Serializable
{
/**
* #ORM\ManyToOne(targetEntity="AppBundle\Entity\Company", inversedBy="users")
* #ORM\JoinColumn(name="company_id", referencedColumnName="id", nullable=false)
*/
private $company;
}
class Company
{
/**
* #ORM\OneToMany(targetEntity="AppBundle\Entity\User", mappedBy="company")
*/
private $users;
}

Answer 1

Repository returns you an ArrayCollection of entities, not a single entity, therefore you need to access each of them separately.
This should work:
foreach($companies as $company) {
$company->getUsers();
}
The problem with the above is that by default it will fetch (lazy load) users from database for each company in separate query (on demand when calling getUsers), which would be very inefficient on larger scale.
There are couple possible solution depending on your needs.
You could configure doctrine to always fetch users with companies, which is called eager fetch.
Having fetched users, you can merge ArrayCollections (and remove duplicates if needed), to achieve single collection containing all users.
Other way could be to fetch companies with users by creating sufficient DQL query in a custom method of you company's repository. If you need only users and don't need companies, then it could be a query that only fetches users without companies.

Answer 2

Try something like this in your User-Repository:
public function getAllUsersFromCompanies($ids)
{
$qb = $this->createQueryBuilder('u');
$qb->leftJoin('u.company', 'c')
->where('c.id IN :ids')
->setParameter('ids', $ids)
->getQuery();
return $query->getResult();
}
We are joining the user table with the company table here, which gives us the company for each user. Then, we filter out every user, that has the wrong company.

Answer 3

You can e.g. fetch all Comapany entities with users with one query:
$companies = $em->createQueryBuilder()
->select('c, u')
->from('AppBundle:Company', 'c')
// or left join based on you needs
->innerJoin('c.users', 'u')
->getQuery()
->getResult();
This will not result in queries when fetching company users.