CakePHP Paginator: get first item from next page? - php

Question

I have a table that contains different versions of a text. I want to display the diffs of each version with the previous version. I also want to paginate through the versions, in case there are more than 20. However, to diff the last text on each page I would need the first text of the next page. I cannot just make the page size one larger (21 in this case), because the second page would skip its first entity, and the third its first two etc.
$config = $this->Paginator->getConfig();
$this->Paginator->setConfig('limit', $config['limit'] + 1);
$inscriptions = $this->paginate($query);
I might instead be able to solve the problem by making a separate ->paginate() call for the single entity, but I would rather not execute a second query if possible.
$inscriptions = $this->paginate($query);
$config = $this->Paginator->getConfig();
$this->Paginator->setConfig([
'limit' => 1,
'page' => ($config['page'] * $config['limit']) + 1
]);
$inscriptions[] = $this->paginate($query)->first();
Is there a way to skip the first n results? In that case I could set the page size to 21 but set the page number to 1, and skip the first ((old page number - 1) * old page size) entities.

Answer 1

It is possible to make a custom paginator that extends the default one, but functions as described:
<?php
namespace App\Datasource;
use Cake\Core\InstanceConfigTrait;
use Cake\Datasource\Paginator;
use Cake\Datasource\QueryInterface;
use Cake\Datasource\RepositoryInterface;
class DiffPaginator extends Paginator
{
use InstanceConfigTrait;
protected function getQuery(RepositoryInterface $object, ?QueryInterface $query = null, array $data): QueryInterface
{
$data['options']['offset'] = ($data['options']['page'] - 1) * $data['options']['limit'];
$data['options']['limit'] += 1;
unset($data['options']['page']);
return parent::getQuery($object, $query, $data);
}
protected function buildParams(array $data): array
{
$paging = parent::buildParams($data);
if ($paging['current'] == $paging['perPage'] + 1) {
$paging['current'] -= 1;
}
return $paging;
}
}
In your controller then use the following:
$this->Paginator->setPaginator(new DiffPaginator);