EZP-27458: Aggregation API

[adamwojs]

Description

Implementation of Aggregation API (see ezsystems/ezplatform-kernel#94) for Solr Search Engine.  

Sequence diagram

Extension points

The following extension points has been introduced in order to be able to handle custom aggregations. 

EzSystems\EzPlatformSolrSearchEngine\Query\AggregationVisitor

AggregationVisitor is responsible for building aggregation query base on aggregation definition.

<?php

namespace EzSystems\EzPlatformSolrSearchEngine\Query;

use eZ\Publish\API\Repository\Values\Content\Query\AggregationInterface;

interface AggregationVisitor
{
    /**
     * Check if visitor is applicable to current aggreagtion.
     */
    public function canVisit(AggregationInterface $aggregation, array $languageFilter): bool;

    /**
     * @return string[]
     */
    public function visit(
        AggregationVisitor $dispatcherVisitor,
        AggregationInterface $aggregation,
        array $languageFilter
    ): array;
} 

EzSystems\EzPlatformSolrSearchEngine\Query\AggregationVisitor::visit result will be encoded as JSON and should be compatible with JSON Facet API described here: https://lucene.apache.org/solr/guide/7_7/json-facet-api.html. 

AggregationVisitor implementations should be registered as a service and tagged with ezplatform.search.solr.query.content.aggregation_visitor and/or ezplatform.search.solr.query.location.aggregation_visitor tag.

EzSystems\EzPlatformSolrSearchEngine\ResultExtractor\AggregationResultExtractor

AggregationResultExtractor is responsible for transforming raw aggregation results into AggregationResult object. 

<?php

namespace EzSystems\EzPlatformSolrSearchEngine\ResultExtractor;

use eZ\Publish\API\Repository\Values\Content\Query\AggregationInterface;
use eZ\Publish\API\Repository\Values\Content\Search\AggregationResult;
use stdClass;

interface AggregationResultExtractor
{
    public function canVisit(AggregationInterface $aggregation, array $languageFilter): bool;

    public function extract(AggregationInterface $aggregation, array $languageFilter, stdClass $data): AggregationResult;
} 

AggregationResultExtractor implementations should be registered as a service and tagged with ezplatform.search.solr.query.content.aggregation_result_extractor and/or ezplatform.search.solr.query.location.aggregation_result_extractor tag. 

Deprecations

The following classes/interfaces has been deprecated:

• \EzSystems\EzPlatformSolrSearchEngine\Query\FacetFieldVisitor
• \EzSystems\EzPlatformSolrSearchEngine\Query\FacetBuilderVisitor and all inheriting classes

as well as the following services/aliases:

• ezpublish.search.solr.result_extractor.native
• ezpublish.search.solr.result_extractor

BC Breaks

• Added $languageSettings parameter to EzSystems\EzPlatformSolrSearchEngine\Query\QueryConverter::convert
• Added $languageFilter and $aggregations parameters to EzSystems\EzPlatformSolrSearchEngine\ResultExtractor::extract

Links

• EZP-27458: Provided Aggregation API ezplatform-kernel#94
• https://lucene.apache.org/solr/guide/7_7/json-facet-api.html

Checklist

• Rebase after Use code style rules from ezplatform-code-style #194 merge
• Code follows the code style of this project (use $ composer fix-cs).
• Change requires a change to the documentation.
• Code is ready for a review.