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File: vendor/doctrine/orm/docs/en/tutorials/pagination.rst

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File: vendor/doctrine/orm/docs/en/tutorials/pagination.rst
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Pagination
==========

.. versionadded:: 2.2

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``.

.. code-block:: php

    <?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
.