Add filterOnly facet modifier to the configuration

app/code/community/Algolia/Algoliasearch/Block/System/Config/Form/Field/Facets.php

@@ -5,6 +5,10 @@
  */
 class Algolia_Algoliasearch_Block_System_Config_Form_Field_Facets extends Algolia_Algoliasearch_Block_System_Config_Form_Field_AbstractField
 {
+    const SEARCHABLE = '1';
+    const NOT_SEARCHABLE = '2';
+    const FILTER_ONLY = '3';
+
     protected $_isQueryRulesDisabled;
 
     public function __construct()
@@ -44,10 +48,11 @@ public function __construct()
                     'style' => 'width: 100px;',
                 ),
                 'searchable' => array(
-                    'label' => 'Searchable?',
+                    'label' => 'Modifier',
                     'options' => array(
-                        '1' => 'Yes',
-                        '2' => 'No'
+                        self::SEARCHABLE => 'Searchable',
+                        self::NOT_SEARCHABLE => 'Not Searchable',
+                        self::FILTER_ONLY => 'Filter Only',
                     ),
                     'rowMethod' => 'getSearchable',
                 ),

app/code/community/Algolia/Algoliasearch/Helper/Entity/Producthelper.php

@@ -258,8 +258,12 @@ public function setSettings($storeId, $saveToTmpIndicesToo = false)
                 }
             } else {
                 $attribute = $facet['attribute'];
-                if (array_key_exists('searchable', $facet) && $facet['searchable'] === '1') {
-                    $attribute = 'searchable('.$attribute.')';
+                if (array_key_exists('searchable', $facet)) {
+                    if ($facet['searchable'] === Algolia_Algoliasearch_Block_System_Config_Form_Field_Facets::SEARCHABLE) {
+                        $attribute = 'searchable(' . $attribute . ')';
+                    } elseif ($facet['searchable'] === Algolia_Algoliasearch_Block_System_Config_Form_Field_Facets::FILTER_ONLY) {
+                        $attribute = 'filterOnly(' . $attribute . ')';
+                    }
                 }
 
                 $attributesForFaceting[] = $attribute;

app/code/community/Algolia/Algoliasearch/etc/system.xml

@@ -406,6 +406,8 @@
                                 <br>
                                 Set facet as searchable if you want your customers to be able to <a target="_blank" href="https://www.algolia.com/doc/api-reference/api-methods/search-for-facet-values/">search for facet values</a>. It's handy when a facet has a lot of values.
                                 <br>
+                                Set facet as Filter Only if only the <a target="_blank" href="https://www.algolia.com/doc/api-reference/api-parameters/attributesForFaceting/#parameter-option-filteronly">filtering feature</a> is needed.
+                                <br>
                                 Facets' documentation: <a target="_blank" href="https://community.algolia.com/magento/doc/m1/indexing/?utm_source=magento&utm_medium=extension&utm_campaign=magento_1&utm_term=shop-owner&utm_content=doc-link#facets">https://community.algolia.com/magento/doc/m1/indexing/#facets</a>
                                 <br>
                                 <br>