symfony - Doctrine : Pagination with left Joins

Question

I would like to paginate a complex request with at least 2 left joins, but the pagination bundle I'm using (KnpPaginationBundle) can't tell Doctrine how to count the result (which is needed for the pagination process), and keep having this Exception.

Cannot count query which selects two FROM components, cannot make distinction

Here is a sample request built with the Doctrine QueryBuilder.

public function findGroupsByUser(User $user, $listFilter, $getQuery = false, $order = 'ASC')
{
    $query = $this->createQueryBuilder('r')
        ->select('r as main,g')
        ->select('r as main,g, count(gg) as members')
        ->leftjoin('r.group', 'g')
        ->innerjoin('MyBundle:GroupMemberRel', 'gg', 'WITH', 'r.group = gg.group')
        ->addGroupBy('g.groupId')
        ->add('orderBy', 'g.name ' . $order);
   if ($getQuery == true) {
        return $query;
    }

    return $query->getQuery()->getResult();
}

Then I give this request to the knp_paginator service, and then I've got the exception

    $groupQuery = $this->em->getRepository('MyBundle:GroupMemberRel')->findGroupsByUser($user, $listFilter, true);
    $paginator = $this->container->get('knp_paginator');
    /* @var $groups KnpComponentPagerPaginationPaginationInterface */
    $groups = $paginator->paginate(
        $groupQuery, $this->container->get('request')->query->get('page', 1), 10 /* limit per page */
    );

Any idea on how to paginate over a complex request, I'm pretty sure this use-case is common, don't want to hydrate my result after the pagination.

Answer 1

For anyone looking for an answer about this, there is a good solution at: https://github.com/KnpLabs/KnpPaginatorBundle/blob/master/Resources/doc/manual_counting.md

$paginator = new Paginator;

// determine the count of the entire result set
$count = $entityManager
    ->createQuery('SELECT COUNT(c) FROM EntityCompositeKey c')
    ->getSingleScalarResult();

// create a query to be used with the paginator, and specify a hint
$query = $entityManager
     ->createQuery('SELECT c FROM EntityCompositeKey c')
     ->setHint(
        'knp_paginator.count', 
        $count
    );

// paginate, and set "disctinct" option to false
$pagination = $paginator->paginate(
    $query, 
    1, 
    10, 
    array(
        'distinct' => false,
    )
);

Basically, what you are doing, is you are creating your own 'count' query and instruct knp paginator to use this.