[Backport] Fixed Issue : Search REST API returns wrong total_count

lib/internal/Magento/Framework/Search/Adapter/Mysql/Adapter.php

@@ -48,6 +48,16 @@ class Adapter implements AdapterInterface
      */
     private $temporaryStorageFactory;
 
+    /**
+     * Query Select Parts to be skipped when prepare query for count
+     *
+     * @var array
+     */
+    private $countSqlSkipParts = [
+        \Magento\Framework\DB\Select::LIMIT_COUNT => true,
+        \Magento\Framework\DB\Select::LIMIT_OFFSET => true,
+    ];
+
     /**
      * @param Mapper $mapper
      * @param ResponseFactory $responseFactory
@@ -85,6 +95,7 @@ public function query(RequestInterface $request)
         $response = [
             'documents' => $documents,
             'aggregations' => $aggregations,
+            'total' => $this->getSize($query)
         ];
         return $this->responseFactory->create($response);
     }
@@ -105,10 +116,47 @@ private function getDocuments(Table $table)
     }
 
     /**
+     * Get connection.
+     *
      * @return false|\Magento\Framework\DB\Adapter\AdapterInterface
      */
     private function getConnection()
     {
         return $this->resource->getConnection();
     }
+
+    /**
+     * Get rows size
+     *
+     * @param Select $query
+     * @return int
+     */
+    private function getSize(Select $query): int
+    {
+        $sql = $this->getSelectCountSql($query);
+        $parentSelect = $this->getConnection()->select();
+        $parentSelect->from(['core_select' => $sql]);
+        $parentSelect->reset(\Magento\Framework\DB\Select::COLUMNS);
+        $parentSelect->columns('COUNT(*)');
+        $totalRecords = $this->getConnection()->fetchOne($parentSelect);
+
+        return (int) $totalRecords;
+    }
+
+    /**
+     * Reset limit and offset
+     *
+     * @param Select $query
+     * @return Select
+     */
+    private function getSelectCountSql(Select $query): Select
+    {
+        foreach ($this->countSqlSkipParts as $part => $toSkip) {
+            if ($toSkip) {
+                $query->reset($part);
+            }
+        }
+
+        return $query;
+    }
 }

lib/internal/Magento/Framework/Search/Adapter/Mysql/ResponseFactory.php

@@ -65,7 +65,8 @@ public function create($rawResponse)
             \Magento\Framework\Search\Response\QueryResponse::class,
             [
                 'documents' => $documents,
-                'aggregations' => $aggregations
+                'aggregations' => $aggregations,
+                'total' => $rawResponse['total']
             ]
         );
     }

lib/internal/Magento/Framework/Search/Response/QueryResponse.php

@@ -29,14 +29,21 @@ class QueryResponse implements ResponseInterface
      */
     protected $aggregations;
 
+    /**
+     * @var int
+     */
+    private $total;
+
     /**
      * @param Document[] $documents
      * @param AggregationInterface $aggregations
+     * @param int $total
      */
-    public function __construct(array $documents, AggregationInterface $aggregations)
+    public function __construct(array $documents, AggregationInterface $aggregations, int $total = 0)
     {
         $this->documents = $documents;
         $this->aggregations = $aggregations;
+        $this->total = $total;
     }
 
     /**
@@ -65,4 +72,12 @@ public function getAggregations()
     {
         return $this->aggregations;
     }
+
+    /**
+     * @inheritdoc
+     */
+    public function getTotal(): int
+    {
+        return $this->total;
+    }
 }

lib/internal/Magento/Framework/Search/ResponseInterface.php

@@ -16,4 +16,11 @@ interface ResponseInterface extends \IteratorAggregate, \Countable
      * @return \Magento\Framework\Api\Search\AggregationInterface
      */
     public function getAggregations();
+
+    /**
+     * Return total count of items.
+     *
+     * @return int
+     */
+    public function getTotal(): int;
 }

lib/internal/Magento/Framework/Search/SearchResponseBuilder.php

@@ -9,6 +9,9 @@
 use Magento\Framework\Api\Search\DocumentFactory;
 use Magento\Framework\Api\Search\SearchResultFactory;
 
+/**
+ * Builder for search response.
+ */
 class SearchResponseBuilder
 {
     /**
@@ -35,6 +38,8 @@ public function __construct(
     }
 
     /**
+     * Build search result by search response.
+     *
      * @param ResponseInterface $response
      * @return SearchResultInterface
      */
@@ -46,7 +51,7 @@ public function build(ResponseInterface $response)
         $documents = iterator_to_array($response);
         $searchResult->setItems($documents);
         $searchResult->setAggregations($response->getAggregations());
-        $searchResult->setTotalCount(count($documents));
+        $searchResult->setTotalCount($response->getTotal());
 
         return $searchResult;
     }

lib/internal/Magento/Framework/Search/Test/Unit/Adapter/Mysql/AdapterTest.php

@@ -155,15 +155,22 @@ public function testQuery()
                     'aggregation2' => [2, 4],
                 ],
             ],
+            'total' => 1
         ];
 
         $select = $this->getMockBuilder(\Magento\Framework\DB\Select::class)
             ->disableOriginalConstructor()
             ->getMock();
-        $this->connectionAdapter->expects($this->once())
+
+        $this->connectionAdapter->expects($this->exactly(2))
             ->method('select')
             ->willReturn($select);
 
+        $this->connectionAdapter->expects($this->once())
+            ->method('fetchOne')
+            ->with($select)
+            ->willReturn($selectResult['total']);
+
         $table = $this->getMockBuilder(\Magento\Framework\DB\Ddl\Table::class)
             ->disableOriginalConstructor()
             ->getMock();

lib/internal/Magento/Framework/Search/Test/Unit/Adapter/Mysql/ResponseFactoryTest.php

@@ -49,6 +49,7 @@ public function testCreate()
                 ['title' => 'twoTitle', 'description' => 'twoDescription'],
             ],
             'aggregations' => [],
+            'total' => 2
         ];
 
         $this->documentFactory->expects($this->at(0))->method('create')
@@ -61,7 +62,7 @@ public function testCreate()
         $this->objectManager->expects($this->once())->method('create')
             ->with(
                 $this->equalTo(\Magento\Framework\Search\Response\QueryResponse::class),
-                $this->equalTo(['documents' => ['document1', 'document2'], 'aggregations' => null])
+                $this->equalTo(['documents' => ['document1', 'document2'], 'aggregations' => null, 'total' => 2])
             )
             ->will($this->returnValue('QueryResponseObject'));
 

lib/internal/Magento/Framework/Search/Test/Unit/Response/QueryResponseTest.php

@@ -46,6 +46,7 @@ protected function setUp()
             [
                 'documents' => $this->documents,
                 'aggregations' => $this->aggregations,
+                'total' => 1
             ]
         );
     }

lib/internal/Magento/Framework/Search/Test/Unit/SearchResponseBuilderTest.php

@@ -67,7 +67,7 @@ public function testBuild()
 
         /** @var QueryResponse|\PHPUnit_Framework_MockObject_MockObject $response */
         $response = $this->getMockBuilder(\Magento\Framework\Search\Response\QueryResponse::class)
-            ->setMethods(['getIterator', 'getAggregations'])
+            ->setMethods(['getIterator', 'getAggregations', 'getTotal'])
             ->disableOriginalConstructor()
             ->getMockForAbstractClass();
         $response->expects($this->any())
@@ -76,6 +76,9 @@ public function testBuild()
         $response->expects($this->once())
             ->method('getAggregations')
             ->willReturn($aggregations);
+        $response->expects($this->any())
+            ->method('getTotal')
+            ->willReturn(1);
 
         $result = $this->model->build($response);