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Pagination

Starting with version 2.2 Doctrine ships with a Paginator for DQL queries. It has a very simple API and implements the SPL interfaces Countable and IteratorAggregate.

<?php
use Doctrine\ORM\Tools\Pagination\Paginator;

$dql = "SELECT p, c FROM BlogPost p JOIN p.comments c";
$query = $entityManager->createQuery($dql)
                       ->setFirstResult(0)
                       ->setMaxResults(100);

$paginator = new Paginator($query, $fetchJoinCollection = true);

$c = count($paginator);
foreach ($paginator as $post) {
    echo $post->getHeadline() . "\n";
}

Paginating Doctrine queries is not as simple as you might think in the beginning. If you have complex fetch-join scenarios with one-to-many or many-to-many associations using the "default" LIMIT functionality of database vendors is not sufficient to get the correct results.

By default the pagination extension does the following steps to compute the correct result:

  • Perform a Count query using DISTINCT keyword.
  • Perform a Limit Subquery with DISTINCT to find all ids of the entity in from on the current page.
  • Perform a WHERE IN query to get all results for the current page.

This behavior is only necessary if you actually fetch join a to-many collection. You can disable this behavior by setting the $fetchJoinCollection flag to false; in that case only 2 instead of the 3 queries described are executed. We hope to automate the detection for this in the future.