Show result JSON only on failure, otherwise redirect to route 'zfcuser'.

composer.json

@@ -18,7 +18,8 @@
     ],
     "require": {
         "php": "^5.5|^7.0",
-        "zf-commons/zfc-user": "^3.0"
+        "zf-commons/zfc-user": "^3.0",
+		"phpoption/phpoption": "^1.0"
     },
     "autoload": {
         "psr-4": {

src/Controller/Substitute.php

@@ -18,13 +18,19 @@ public function __construct(SubstituteService $substituteService) {
     }
 
     public function substituteAction() {
-        $result = $this->substituteService->substitute($this->params('user'));
-        return new JsonModel($result);
+        $errorOption = $this->substituteService->substitute($this->params('user'));
+        foreach ($errorOption as $error) {
+            return new JsonModel(['error' => $error]);
+        }
+        return $this->redirect()->toRoute('zfcuser');
     }
 
     public function unsubstituteAction() {
-        $result = $this->substituteService->unsubstitute();
-        return new JsonModel($result);
+        $errorOption = $this->substituteService->unsubstitute();
+        foreach ($errorOption as $error) {
+            return new JsonModel(['error' => $error]);
+        }
+        return $this->redirect()->toRoute('zfcuser');
     }
 
 }

src/Service/Substitute.php

@@ -5,6 +5,7 @@
 use Zend\Authentication\Storage\StorageInterface;
 use Zend\Authentication\AuthenticationService;
 use ZfcUser\Mapper\User as UserMapper;
+use PhpOption\Option as PhpOption;
 
 class Substitute {
 
@@ -32,38 +33,39 @@ public function __construct(
         $this->setStorage($storage);
     }
 
+    /**
+     * @param string $userId
+     * @return PhpOption error reason
+     */
     public function substitute($userId) {
-        $error['result'] = 'error';
-        $success['result'] = 'success';
-
         $identity = $this->getAuthService()->getIdentity();
         if (!$identity) {
-            return $error + ['message' => 'Not logged in'];
+            return PhpOption::ensure('Not logged in');
         }
         if (!$this->getStorage()->isEmpty()) {
-            return $error + ['message' => 'Already substituted'];
+            return PhpOption::ensure('Already substituted');
         }
         if (!$this->getUserMapper()->findById($userId)) {
-            return $error + ['message' => 'Substitution user does not exist'];
+            return PhpOption::ensure('Substitution user does not exist');
         }
 
         $this->getStorage()->write($identity);
         $this->getAuthService()->getStorage()->write($userId);
-        return $success;
+        return PhpOption::ensure(null);
     }
 
+    /**
+     * @return PhpOption error reason
+     */
     public function unsubstitute() {
-        $error['result'] = 'error';
-        $success['result'] = 'success';
-
         if ($this->getStorage()->isEmpty()) {
-            return $error + ['message' => 'Not substituted'];
+            return PhpOption::ensure('Not substituted in the first place');
         }
         $originalUser = $this->getStorage()->read();
         $this->getStorage()->clear();
 
         $this->getAuthService()->getStorage()->write($originalUser->getId());
-        return $success;
+        return PhpOption::ensure(null);
     }
 
     public function isSubstituted() {