Support offset/slice in pagination

[tacman]

Description

I would like to use API Platform to get a slice of the results, not a page.

Example

/api/...?offset=422&items_per_page=81

A javascript library I'm using for infinite scrolling fetches more than a "page". Currently within API Platform, the offset is calculated from the page and returned, I'd like to override what's returned.

        $firstResult = ($page - 1) * $itemsPerPage;
// ...
       return [$firstResult, $itemsPerPage];

I considered extending the Doctrine ORM paginator class, but it's marked as final.

There's probably an elegant solution here somewhere, but I can't find it, so maybe it can be added. What I want is identical to the Doctrine ORM provider with pagination, so ideally I'd like to leverage the existing code and simply change the first result offset.

[tacman]

@dunglas , what do you think of a PR that adds "offset" (or "starting_at") to the arguments, then

Currently the pagination extension that returns a slice of the results given page_number and records_per_page, e.g. page 3, 50 records, getPagination() return [100, 50]

// vendor/api-platform/core/src/Bridge/Doctrine/Orm/Extension/PaginationExtension.php:121

public function applyToCollection(QueryBuilder $queryBuilder, QueryNameGeneratorInterface $queryNameGenerator, string $resourceClass, string $operationName = null, array $context = [])
    {
        if (null === $pagination = $this->getPagination($queryBuilder, $resourceClass, $operationName, $context)) {
            return;
        }

        [$offset, $limit] = $pagination;
        $queryBuilder
            ->setFirstResult($offset)
            ->setMaxResults($limit);
    }

What I want is just a slice, not really a paginator. I'm not sure if the best approach is to override the paginator, or create a custom data collector, but what about building it the paginator?

                ['arg_name' => 'offset', 'type' => 'int', 'default' => 0],
                ['arg_name' => 'offsetParameterName', 'type' => 'string', 'default' => 'offset'],
                ['arg_name' => 'enabledOffset', 'type' => 'boolean', 'default' => false],

Then if offset were enabled, the paginator would return the values passed in and not need to calculate the offset / limit as it does now given the page number.

    public function applyToCollection(QueryBuilder $queryBuilder, QueryNameGeneratorInterface $queryNameGenerator, string $resourceClass, string $operationName = null, array $context = [])
    {
       // if offset it enabled, use it, otherwise call the paginator..
        [$offset, $limit] = [41, 220];
        $queryBuilder
            ->setFirstResult($offset)
            ->setMaxResults($limit);
    }

I've asked this on stackoverflow, too.

https://stackoverflow.com/questions/72583686/override-doctrine-pagination-to-perform-slice-in-api-platform-paginationextensio

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[maySaghira]

@tacman plz I need the same aspect, the param was added or not ?

[tacman]

No, and I don't know how to override it. @dunglas , would you accept a PR if this were added? Or provide direction in how to implement it with a custom paginator?

[maySaghira]

Hello! I've implement a workaround for that: 1- disable pagination. 2- use an extension on QueryCollectionExtensionInterface where get the param from request.

<?php

namespace App\Extension;

use ApiPlatform\Doctrine\Orm\Extension\QueryCollectionExtensionInterface;
use ApiPlatform\Doctrine\Orm\Util\QueryNameGeneratorInterface;
use ApiPlatform\Metadata\Operation;
use Doctrine\ORM\QueryBuilder;
use Symfony\Component\DependencyInjection\ContainerInterface;
use ApiPlatform\Metadata\CollectionOperationInterface;

final class CurrentCollectionExtension implements QueryCollectionExtensionInterface
{
    public function __construct()
    {
    }
    public function applyToCollection(
        QueryBuilder $queryBuilder,
        QueryNameGeneratorInterface $queryNameGenerator,
        string $resourceClass,
        Operation $operation = null,
        array $context = []
    ): void {
        if ($operation instanceof CollectionOperationInterface) {
            $this->addOffsetLimit($queryBuilder, $context);
        }

    }

    private function addOffsetLimit(QueryBuilder $queryBuilder, array $context = []): void
    {
        $offset = $context['filters']['offset'] ?? 0;
        $limit = $context['filters']['limit'];

        $queryBuilder->setFirstResult($offset)
                     ->setMaxResults($limit);
    }
}

3- decorate OpenApiFactory to add limit and offset for params in query for every collection operation.

public function __invoke(array $context = []): OpenApi
 {
     $openApi = $this->decorated->__invoke($context);
     $openApiPaths = $openApi->getPaths();
     foreach (array_keys($openApiPaths->getPaths()) as $path) {
         $pathItem = $openApiPaths->getPath($path);
         $operation = $pathItem->getGet();

         if ($operation !== null && str_ends_with($operation->getOperationId(), '_get_collection')) {
             $openApiPaths->addPath(
                 $path,
                 $pathItem->withGet(
                     $operation->withParameters(array_merge(
                         [new Model\Parameter('limit', 'query', '', false, false, true, ['type' => 'integer']),
                         new Model\Parameter('offset', 'query', '', false, false, true, ['type' => 'integer'])],
                         $operation->getParameters()
                     ))
                 )
             );
         }
     }

     return $openApi;
 }

And do not forget to add the extension in the service config

App\Extension\CurrentCollectionExtension:
        tags:
            - { name: api_platform.collection_extension, priority: 100 }

Hope it helps.