Introduction

The Facets module allows site builders to easily create and manage faceted search interfaces.

Features

If you are the developer of a search API backend implementation and want to support facets with your service class, too, you'll have to support the "search_api_facets" feature. In short, when executing a query, you'll have to return facet terms and counts according to the query's "search_api_facets" option. For the module to be able to tell that your server supports facets, you will also have to change your service's supportsFeature() method to something like the following:

  public function getSupportedFeatures() {
    return ['search_api_facets'];
  }

If you don't do that, there's no way for the facet source to pick up facets.

The `search_api_facets`` option looks as follows:

$query->setOption('search_api_facets', [
  $facet_id => [
    // The Search API field ID of the field to facet on.
    'field' => (string),
    // The maximum number of filters to retrieve for the facet.
    'limit' => (int),
    // The facet operator: "and" or "or".
    'operator' => (string),
    // The minimum count a filter/value must have been returned.
    'min_count' => (int),
    // Whether to retrieve a facet for "missing" values.
    'missing' => (bool),
  ],
  // …
]);

The structure of the returned facets array should look like this:

$results->setExtraData('search_api_facets', [
  $facet_id => [
    [
      'count' => (int),
      'filter' => (string),
    ],
    // …
  ],
  // …
]);

A filter is a string with one of the following forms: - "VALUE": Filter by the literal value VALUE (always include the quotes, not only for strings). - [VALUE1 VALUE2]: Filter for a value between VALUE1 and VALUE2. Use parentheses for excluding the border values and square brackets for including them. An asterisk () can be used as a wildcard. E.g., ( 0) or [* 0) would be a filter for all negative values. - !: Filter for items without a value for this field (i.e., the "missing" facet).