[GroupModel] import simpleGroups into SQL

src/graphql/models/groupModel.ts

@@ -55,7 +55,15 @@ export class GroupModel {
                     return null;
             }
         }
-        return null;
+        else { //maybe the simple group isn't buffered yet => check in the LDAP
+            let sg = SimpleGroup.tryCreate(gid);
+
+            if(sg) { //group found => insert into groups table 
+                knex('groups').insert({gid: gid, type: 'simple'}).then(); // <-- .then() necessary for command execution
+            }
+
+            return sg;
+        }
     }
 
     async getGroup(gid: string): Promise<Group> {