Add facet or aggregatable option to schema index field definition

[alexander-schranz]

The Idea:

Schema Definition

For ecommerce websites it would great if we could support some kind of facets or aggregations to allow better filtering.

The first case for supporting this is adding it to the schema metadata via:

new Field\TextField(name: 'category', filterable: true, facet: true);
new Field\IntegerField(name: 'downloads', filterable: true, facet: true);
new Field\FloatField(name: 'rating', filterable: true, facet: true);
new Field\DateTimeField(name: 'createdAt', filterable: true, facet: true);
new Field\BooleanField(name: 'isSpecial', filterable: true, facet: true);

Note

Not sure if aggregatable is a better name in the schema index field definition.

new Field\TextField(name: 'category', filterable: true, aggregatable: true);

Warning

Maybe there need to be no different between filterable or aggregatable / facet > currently all engines seems support facets for filterable fields. If not required we can remove the first two commits.

Search with Facet Result

The facet should be possible to add to the SearchBuilder:

$result = $this->engine->createSearchBuilder('blog')
    ->addFilter(/* ... */)
    ->addFacet(new TermFacet(field: 'category')) // TODO
    ->addFacet(new CountFacet(field: 'category')) // alternative to Term?
    ->addFacet(new MinMaxFacet(field: 'category')) // TODO
    ->getResult();

Note

Not sure if addAggregation is a better with:

->addAggregation(new TermAggregation(field: 'category')) // TODO
->addAggregation(new CountAggregation(field: 'category')) // alternative to Term?
->addAggregation(new MinMaxAggregation(field: 'category')) // TODO

We need maybe know what kind of facets:

Todo Facets / Aggregations

For the first case I think Term aggregation / facet is best way yet to support categorized search results. Min/Max seems not all engine supported so we will keep that outside currently. AVG / SUM is in Algolia for example return when do facetStats to get min, max, avg, sum but not sure about AVG / SUM as I don't know yet a real usecase for searches and ecommerce sites yet for it.

• Term
• Min/Max / range ?
• AVG / SUM ? (don't know usage about this yet)

ToDo Decide naming

• facet vs. aggregatable

ToDo Search Engines

• Memory
• Elasticsearch
• Opensearch
• Algolia
• Meilisearch
• Typesense
• Solr
• Typesense
• Loupe

fixes #182