Add The Ability To Limit Autocomplete Results

app/code/Magento/CatalogSearch/Model/Autocomplete/DataProvider.php

@@ -10,9 +10,16 @@
 use Magento\Search\Model\QueryFactory;
 use Magento\Search\Model\Autocomplete\DataProviderInterface;
 use Magento\Search\Model\Autocomplete\ItemFactory;
+use Magento\Framework\App\Config\ScopeConfigInterface as ScopeConfig;
+use Magento\Store\Model\ScopeInterface;
 
 class DataProvider implements DataProviderInterface
 {
+    /**
+     * Autocomplete limit
+     */
+    const CONFIG_AUTOCOMPLETE_LIMIT = 'catalog/search/autocomplete_limit';
+
     /**
      * Query factory
      *
@@ -27,16 +34,29 @@ class DataProvider implements DataProviderInterface
      */
     protected $itemFactory;
 
+    /**
+     * Limit
+     *
+     * @var int
+     */
+    protected $limit;
+
     /**
      * @param QueryFactory $queryFactory
      * @param ItemFactory $itemFactory
      */
     public function __construct(
         QueryFactory $queryFactory,
-        ItemFactory $itemFactory
+        ItemFactory $itemFactory,
+        ScopeConfig $scopeConfig
     ) {
         $this->queryFactory = $queryFactory;
         $this->itemFactory = $itemFactory;
+
+        $this->limit = (int) $scopeConfig->getValue(
+            self::CONFIG_AUTOCOMPLETE_LIMIT,
+            ScopeInterface::SCOPE_STORE
+        );
     }
 
     /**
@@ -58,7 +78,7 @@ public function getItems()
                 $result[] = $resultItem;
             }
         }
-        return $result;
+        return ($this->limit) ? array_splice($result, 0, $this->limit) : $result;
     }
 
     /**

app/code/Magento/CatalogSearch/Test/Unit/Model/Autocomplete/DataProviderTest.php

@@ -30,6 +30,11 @@ class DataProviderTest extends \PHPUnit\Framework\TestCase
      */
     private $suggestCollection;
 
+    /**
+     * @var integer
+     */
+    private $limit = 3;
+
     protected function setUp()
     {
         $helper = new ObjectManager($this);
@@ -60,11 +65,20 @@ protected function setUp()
             ->setMethods(['create'])
             ->getMock();
 
+        $scopeConfig = $this->getMockBuilder(\Magento\Framework\App\Config\ScopeConfigInterface::class)
+            ->setMethods(['getValue'])
+            ->disableOriginalConstructor()
+            ->getMockForAbstractClass();
+        $scopeConfig->expects($this->any())
+            ->method('getValue')
+            ->willReturn($this->limit);
+
         $this->model = $helper->getObject(
             \Magento\CatalogSearch\Model\Autocomplete\DataProvider::class,
             [
                 'queryFactory' => $queryFactory,
-                'itemFactory' => $this->itemFactory
+                'itemFactory' => $this->itemFactory,
+                'scopeConfig' => $scopeConfig
             ]
         );
     }
@@ -103,8 +117,10 @@ public function testGetItems()
             ->will($this->returnValue($expected));
 
         $this->itemFactory->expects($this->any())->method('create')->willReturn($itemMock);
+
         $result = $this->model->getItems();
         $this->assertEquals($expected, $result[0]->toArray());
+        $this->assertEquals($this->limit, count($result));
     }
 
     private function buildCollection(array $data)

app/code/Magento/CatalogSearch/etc/adminhtml/system.xml

@@ -32,6 +32,10 @@
                     <comment>Number of popular search terms to be cached for faster response. Use “0” to cache all results after a term is searched for the second time.</comment>
                     <validate>validate-digits</validate>
                 </field>
+                <field id="autocomplete_limit" translate="label" type="text" sortOrder="20" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
+                    <label>Autocomplete Limit</label>
+                    <validate>validate-digits</validate>
+                </field>
             </group>
         </section>
     </system>

app/code/Magento/CatalogSearch/etc/config.xml

@@ -16,6 +16,7 @@
                 <min_query_length>1</min_query_length>
                 <max_query_length>128</max_query_length>
                 <max_count_cacheable_search_terms>100</max_count_cacheable_search_terms>
+                <autocomplete_limit>8</autocomplete_limit>
             </search>
         </catalog>
     </default>