diff --git a/core/Controllers/GroupController.php b/core/Controllers/GroupController.php
index 14e2391aee2bf53b7214b596a04516e029d7c97e..237426b543d92cc05e582bf0db54857fa2d165c2 100644
--- a/core/Controllers/GroupController.php
+++ b/core/Controllers/GroupController.php
@@ -9,12 +9,13 @@ use Psr\Http\Message\ResponseInterface;
 use Respect\Validation\Validator;
 use Slim\Http\Request;
 use Slim\Http\Response;
+use SrcCore\controllers\PreparedClauseController;
 
 class GroupController
 {
-    public function get(RequestInterface $request, ResponseInterface $response)
+    public function get(Request $request, Response $response)
     {
-        if (!ServiceModel::hasService(['id' => 'admin_groups', 'userId' => $_SESSION['user']['UserId'], 'location' => 'apps', 'type' => 'admin'])) {
+        if (!ServiceModel::hasService(['id' => 'admin_groups', 'userId' => $GLOBALS['userId'], 'location' => 'apps', 'type' => 'admin'])) {
             return $response->withStatus(403)->withJson(['errors' => 'Service forbidden']);
         }
 
@@ -26,31 +27,53 @@ class GroupController
         return $response->withJson(['groups' => $groups]);
     }
 
-    public function create(RequestInterface $request, ResponseInterface $response)
+    public function getById(Request $request, Response $response, array $aArgs)
     {
-        if (!ServiceModel::hasService(['id' => 'admin_groups', 'userId' => $_SESSION['user']['UserId'], 'location' => 'apps', 'type' => 'admin'])) {
+        if (!ServiceModel::hasService(['id' => 'admin_groups', 'userId' => $GLOBALS['userId'], 'location' => 'apps', 'type' => 'admin'])) {
+            return $response->withStatus(403)->withJson(['errors' => 'Service forbidden']);
+        }
+
+        $group = GroupModel::getById(['id' => $aArgs['id']]);
+        if (empty($group)) {
+            return $response->withStatus(400)->withJson(['errors' => 'Group not found']);
+        }
+
+        return $response->withJson(['group' => $group]);
+    }
+
+    public function create(Request $request, Response $response)
+    {
+        if (!ServiceModel::hasService(['id' => 'admin_groups', 'userId' => $GLOBALS['userId'], 'location' => 'apps', 'type' => 'admin'])) {
             return $response->withStatus(403)->withJson(['errors' => 'Service forbidden']);
         }
 
         $data = $request->getParams();
 
-        $check = Validator::stringType()->notEmpty()->validate($data['group_desc']);
-        $check = $check && Validator::stringType()->notEmpty()->validate($data['group_id']);
+        $check = Validator::stringType()->notEmpty()->validate($data['group_id']) && preg_match("/^[\w-]*$/", $data['group_id']) && (strlen($data['group_id']) < 32);
+        $check = $check && Validator::stringType()->notEmpty()->validate($data['group_desc']);
         $check = $check && Validator::stringType()->notEmpty()->validate($data['security']['where_clause']);
         $check = $check && Validator::stringType()->notEmpty()->validate($data['security']['maarch_comment']);
-
         if (!$check) {
             return $response->withStatus(400)->withJson(['errors' => 'Bad Request']);
         }
 
+        $existingGroup = GroupModel::getByGroupId(['groupId' => $data['group_id'], 'select' => ['1']]);
+        if (!empty($existingGroup)) {
+            return $response->withStatus(400)->withJson(['errors' => 'Group already exists']);
+        }
+
+        if (!PreparedClauseController::isClauseValid(['clause' => $data['security']['where_clause'], 'userId' => $GLOBALS['userId']])) {
+            return $response->withStatus(400)->withJson(['errors' => _INVALID_CLAUSE]);
+        }
+
         GroupModel::create(['groupId' => $data['group_id'], 'description' => $data['group_desc'], 'clause' => $data['security']['where_clause'], 'comment' => $data['security']['maarch_comment']]);
 
-        $group = GroupModel::getByGroupId(['groupId' => $data['group_id']]);
-        if (!Validator::intType()->notEmpty()->validate($group['id'])) {
+        $group = GroupModel::getByGroupId(['groupId' => $data['group_id'], 'select' => ['id']]);
+        if (empty($group)) {
             return $response->withStatus(500)->withJson(['errors' => 'Group Creation Error']);
         }
 
-        return $response->withJson(['group' => $group]);
+        return $response->withJson(['group' => $group['id']]);
     }
 
     public function update(RequestInterface $request, ResponseInterface $response, $aArgs)
diff --git a/core/Models/GroupModelAbstract.php b/core/Models/GroupModelAbstract.php
index 9c0dac0262365c45de1df5f9aff9547c938e6e69..aea37bf0ed1492522ac01dc3983af24d9fc4cd9b 100755
--- a/core/Models/GroupModelAbstract.php
+++ b/core/Models/GroupModelAbstract.php
@@ -30,7 +30,7 @@ class GroupModelAbstract
         return $aGroups;
     }
 
-    public static function getById(array $aArgs = [])
+    public static function getById(array $aArgs)
     {
         ValidatorModel::notEmpty($aArgs, ['id']);
         ValidatorModel::stringType($aArgs, ['id']);
@@ -42,14 +42,10 @@ class GroupModelAbstract
             'data'      => [$aArgs['id']]
         ]);
 
-        if (empty($aGroups[0])) {
-            return [];
-        }
-
         return $aGroups[0];
     }
 
-    public static function getByGroupId(array $aArgs = [])
+    public static function getByGroupId(array $aArgs)
     {
         ValidatorModel::notEmpty($aArgs, ['groupId']);
         ValidatorModel::stringType($aArgs, ['groupId']);
@@ -61,10 +57,6 @@ class GroupModelAbstract
             'data'      => [$aArgs['groupId']]
         ]);
 
-        if (empty($aGroups[0])) {
-            return [];
-        }
-
         return $aGroups[0];
     }
 
diff --git a/rest/index.php b/rest/index.php
index 5eda195d35c1cf9e575f9caa9cd76a2568768106..48a4508d433b57fe864ce5bd35a9ab9194618436 100755
--- a/rest/index.php
+++ b/rest/index.php
@@ -142,6 +142,7 @@ $app->get('/administration/statuses/new', \Status\controllers\StatusController::
 //groups
 $app->get('/groups', \Core\Controllers\GroupController::class . ':get');
 $app->post('/groups', \Core\Controllers\GroupController::class . ':create');
+$app->get('/groups/{id}', \Core\Controllers\GroupController::class . ':getById');
 $app->put('/groups/{id}', \Core\Controllers\GroupController::class . ':update');
 $app->delete('/groups/{id}', \Core\Controllers\GroupController::class . ':delete');
 $app->get('/groups/{id}/details', \Core\Controllers\GroupController::class . ':getDetailledById');