at the end of the day, it was inevitable

src/CacheBundle/Repository/CommonFeedRepository.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace CacheBundle\Repository;
+
+use Doctrine\ORM\EntityRepository;
+
+/**
+ * Class CommonFeedRepository
+ * @package CacheBundle\Repository
+ */
+class CommonFeedRepository extends EntityRepository
+{
+
+    /**
+     * Get single feed from repository.
+     *
+     * @param integer $id   A Feed entity instance id.
+     * @param integer $user Filter feeds by specified owner if set.
+     *
+     * @return \CacheBundle\Entity\Feed\AbstractFeed|null
+     */
+    public function getOne($id, $user)
+    {
+        $expr = $this->_em->getExpressionBuilder();
+        $condition = $expr->andX($expr->eq('Feed.id', ':id'));
+        $parameters = [ 'id' => $id ];
+
+        if ($user !== null) {
+            $condition->add($expr->eq('Feed.user', ':user'));
+            $parameters['user'] = $user;
+        }
+
+        return $this->createQueryBuilder('Feed')
+            ->where($condition)
+            ->setParameters($parameters)
+            ->getQuery()
+            ->getOneOrNullResult();
+    }
+}