[Laravel] Support for ExistsFilter

[cay89]

Description
I would like to use the ExistsFilter in Laravel a Laravel project using the JSON:API format. Currently, the ExistsFilter is only implemented under Doctrine ORM, but there is no equivalent under src/Laravel/Eloquent/Filter.

Use Case Filtering a resource collection based on whether a nullable field is present or not, via a JSON:API-compliant request.

Example

Query:

GET /books?filter[optional_field]=true

Model:

#[
    ApiResource(
        operations: [
            new GetCollection(
                name: 'books',
                parameters: [
                    new QueryParameter(
                        key: 'filter[optional_field]',
                        filter: ExistsFilter::class,
                        property: 'optional_field',
                    ),
                    // ...
                    new QueryParameter(key: 'sort', filter: SortFilter::class),
                ],
            ),
            // ...
        ],
    ),
]
class Book extends Model
{
}

Expected Outcome This should allow filtering records where optional_field is not null (when true is passed) or is null (when false is passed), similar to how it's done in the Doctrine ORM implementation.

[soyuka]

Can't you use the boolean filter for this ? Or create a custom one its quite accessible looking at our code:

<?php

declare(strict_types=1);

namespace ApiPlatform\Laravel\Eloquent\Filter;

use ApiPlatform\Metadata\JsonSchemaFilterInterface;
use ApiPlatform\Metadata\Parameter;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Database\Eloquent\Model;

final class ExistsFilter implements FilterInterface, JsonSchemaFilterInterface
{
    use QueryPropertyTrait;

    private const BOOLEAN_VALUES = [
        'true' => true,
        'false' => false,
        '1' => true,
        '0' => false,
    ];

    /**
     * @param Builder<Model>       $builder
     * @param array<string, mixed> $context
     */
    public function apply(Builder $builder, mixed $values, Parameter $parameter, array $context = []): Builder
    {
        if (!\is_string($values) || !\array_key_exists($values, self::BOOLEAN_VALUES)) {
            return $builder;
        }

        $property = $this->getQueryProperty($parameter);
        $value = self::BOOLEAN_VALUES[$values];

        $whereClause = $value ? 'whereNotNull' : 'whereNull';

        return $builder->{$whereClause}($property);
    }

    public function getSchema(Parameter $parameter): array
    {
        return [
            'type' => 'boolean',
            'description' => sprintf('Filter on the existence of the "%s" property.', $this->getQueryProperty($parameter)),
        ];
    }
}

These are autoconfigured they should be declared in our Provider automatically.