diff --git a/src/Controller/APIController.php b/src/Controller/APIController.php
index fc51b24f..526360a2 100644
--- a/src/Controller/APIController.php
+++ b/src/Controller/APIController.php
@@ -2,13 +2,12 @@
 
 namespace App\Controller;
 
-use App\Ramcar\BaseController;
-
 use Doctrine\ORM\Query;
 use Doctrine\ORM\QueryBuilder;
 use Doctrine\DBAL\DBALException;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
+use Symfony\Bundle\FrameworkBundle\Controller\Controller;
 
 use App\Ramcar\APIResult;
 use App\Entity\MobileSession;
@@ -16,8 +15,15 @@ use App\Entity\MobileSession;
 use DateTime;
 
 
-class APIController extends BaseController
+class APIController extends Controller
 {
+    protected $session;
+
+    public function __construct()
+    {
+        $this->session = null;
+    }
+
     protected function checkMissingParameters(Request $req, $params = [])
     {
         $missing = [];
@@ -44,16 +50,50 @@ class APIController extends BaseController
         return $missing;
     }
 
+    // TODO: type hint entity manager
     protected function checkAPIKey($em, $api_key)
     {
         // find the api key (session id)
         $session = $em->getRepository(MobileSession::class)->find($api_key);
         if ($session == null)
-            return false;
+            return null;
 
         return $session;
     }
 
+    protected function checkParamsAndKey(Request $req, $em, $params)
+    {
+        // returns APIResult object
+        $res = new APIResult();
+
+        // inject api_key in params
+        $params[] = 'api_key';
+
+        // check missing parameters
+        $missing = $this->checkMissingParameters($req, $params);
+        if (count($missing) > 0)
+        {
+            $miss_string = implode(', ', $missing);
+            $res->setError(true)
+                ->setErrorMessage('Missing parameter(s): ' . $miss_string);
+            return $res;
+        }
+
+        // check api key
+        $sess = $this->checkAPIKey($em, $req->request->get('api_key'));
+        if ($sess == null)
+        {
+            $res->setError(true)
+                ->setErrorMessage('Invalid API Key');
+            return $res;
+        }
+
+        // store session
+        $this->session = $sess;
+
+        return $res;
+    }
+
     public function register(Request $req)
     {
         $res = new APIResult();
@@ -70,7 +110,7 @@ class APIController extends BaseController
         if (count($missing) > 0)
         {
             $params = implode(', ', $missing);
-            $res->setErrorFlag(true)
+            $res->setError(true)
                 ->setErrorMessage('Missing parameter(s): ' . $params);
             return $this->json($res->getReturnResponse());
         }
@@ -126,33 +166,16 @@ class APIController extends BaseController
 
     public function confirmNumber(Request $req)
     {
-        $res = new APIResult();
-
         // check parameters
         $required_params = [
-            'api_key', 
             'phone_number',
         ];
 
-        $missing = $this->checkMissingParameters($req, $required_params);
-        if (count($missing) > 0)
-        {
-            $params = implode(', ', $missing);
-            $res->setErrorFlag(true)
-                ->setErrorMessage('Missing parameter(s): ' . $params);
-            return $this->json($res->getReturnResponse());
-        }
-
-
-        // check api key
+        // check required parameters and api key
         $em = $this->getDoctrine()->getManager();
-        $sess = $this->checkAPIKey($em, $req->request->get('api_key'));
-        if (!$sess)
-        {
-            $res->setErrorFlag(true)
-                ->setErrorMessage('Invalid API Key');
+        $res = $this->checkParamsAndKey($req, $em, $required_params);
+        if ($res->isError())
             return $this->json($res->getReturnResponse());
-        }
 
         // phone number
         $phone_number = $req->request->get('phone_number');
@@ -162,7 +185,7 @@ class APIController extends BaseController
         // TODO: generate code and save
         // use '123456' for now
         $code = '123456';
-        $sess->setConfirmCode($code)
+        $this->session->setConfirmCode($code)
             ->setPhoneNumber($phone_number);
         $em->flush();
 
@@ -178,42 +201,27 @@ class APIController extends BaseController
 
         // check parameters
         $required_params = [
-            'api_key', 
             'code',
         ];
 
-        $missing = $this->checkMissingParameters($req, $required_params);
-        if (count($missing) > 0)
-        {
-            $params = implode(', ', $missing);
-            $res->setErrorFlag(true)
-                ->setErrorMessage('Missing parameter(s): ' . $params);
-            return $this->json($res->getReturnResponse());
-        }
-
-        // check api key
+        // check required parameters and api key
         $em = $this->getDoctrine()->getManager();
-        $sess = $this->checkAPIKey($em, $req->request->get('api_key'));
-        if (!$sess)
-        {
-            $res->setErrorFlag(true)
-                ->setErrorMessage('Invalid API Key');
+        $res = $this->checkParamsAndKey($req, $em, $required_params);
+        if ($res->isError())
             return $this->json($res->getReturnResponse());
-        }
-
-        $code = $req->request->get('code');
 
         // code is wrong
-        if ($sess->getConfirmCode() != $code)
+        $code = $req->request->get('code');
+        if ($this->session->getConfirmCode() != $code)
         {
-            $res->setErrorFlag(true)
+            $res->setError(true)
                 ->setErrorMessage('Wrong confirm code');
             return $this->json($res->getReturnResponse());
         }
 
         // set confirm date
         $date = new DateTime();
-        $sess->setDateConfirmed($date)
+        $this->session->setDateConfirmed($date)
             ->setConfirmed();
         $em->flush();
 
diff --git a/src/Ramcar/APIResult.php b/src/Ramcar/APIResult.php
index 51e1fef4..dce4cf36 100644
--- a/src/Ramcar/APIResult.php
+++ b/src/Ramcar/APIResult.php
@@ -15,7 +15,7 @@ class APIResult
         $this->data = [];
     }
 
-    public function setErrorFlag($flag = true)
+    public function setError($flag = true)
     {
         $this->err_flag = $flag;
         return $this;