Symfony2 + Doctrine - Filtering - sql

Question

I've got a OneToMany relationship where one football team has many players. I want to list all football teams and display the name of the captain for each team.
Each player entity has a foreign key (team_id) and a field 'captain' which is set to 0 or 1. I'm currently running the following query:
$teams = $this
->getDoctrine()
->getRepository('FootballWebsiteBundle:Team')
->createQueryBuilder('t')
->setFirstResult(($pageNumber * $resultPerPage) - $resultPerPage)
->setMaxResults($resultPerPage)
->add('where','t.deleted = 0')
->add('orderBy', 't.name DESC')
->getQuery()->getResult();
Then when I loop through each team in twig I run team.getTeamCaptain().getName() which is a filter within my Team entity:
public function getTeamCaptain() {
$them = $this->players->filter(function($p) {
return $p->getCaptain() == 1;
});
return $them->first();
}
Is there a better way to run this query?

Answer 1

First of all, you may want to fetch-join the players of each retrieved team to avoid having them lazy loaded during rendering of the template. Here's the DQL:
SELECT
t, p
FROM
FootballWebsiteBundle:Team t
LEFT JOIN
t.players p
WHERE
t.deleted = 0
ORDER BY
t.name DESC
Which can be built with following query builder API calls:
$teamsQuery = $this
->getDoctrine()
->getRepository('FootballWebsiteBundle:Team')
->createQueryBuilder('t')
->addSelect('p')
->leftJoin('t.players', 'p')
->add('where','t.deleted = 0')
->add('orderBy', 't.name DESC')
->getQuery()
Then you wrap this query into a Paginator object (since setMaxResults and setFirstResult cannot be trusted when fetch-joining):
$paginator = new \Doctrine\ORM\Tools\Pagination\Paginator($teamsQuery, true);
$teamsQuery
->setFirstResult(($pageNumber * $resultPerPage) - $resultPerPage)
->setMaxResults($resultPerPage)
In your view you can then iterate on the teams like following pseudo-code:
foreach ($paginator as $team) {
echo $team->getTeamCaptain() . "\n";
}
You can also gain some extra performance in your getTeamCaptain method by using the Selectable API:
public function getTeamCaptain() {
$criteria = new \Doctrine\Common\Collections\Criteria();
$criteria->andWhere($criteria->expr()->eq('captain', 1));
return $this->players->matching($criteria)->first();
}
The advantage here is mainly relevant when the association players is not yet initialized, since this will avoid loading it entirely. This is not the case, but I consider it a good practice (instead of re-inventing collection filtering logic).