[#7907] add some use statements

Author: xabbuh

doctrine.rst

@@ -632,6 +632,9 @@ Updating an Object
 Once you've fetched an object from Doctrine, updating it is easy. Suppose
 you have a route that maps a product id to an update action in a controller::
 
+    use AppBundle\Entity\Post;
+    // ...
+
     public function updateAction($productId)
     {
         $em = $this->getDoctrine()->getManager();

doctrine/associations.rst

@@ -273,6 +273,9 @@ When you need to fetch associated objects, your workflow looks just like it
 did before. First, fetch a ``$product`` object and then access its related
 ``Category`` object::
 
+    use AppBundle\Entity\Post;
+    // ...
+
     public function showAction($productId)
     {
         $product = $this->getDoctrine()

doctrine/repository.rst

@@ -86,6 +86,9 @@ entities, ordered alphabetically by name.
 
 You can use this new method just like the default finder methods of the repository::
 
+    use AppBundle\Entity\Post;
+    // ...
+
     $em = $this->getDoctrine()->getManager();
     $products = $em->getRepository(Product::class)
         ->findAllOrderedByName();