public function store(Request $request)
 {
     $this->validate($request, ['title' => 'required|unique:units|max:100']);
     $input = $request->all();
     $group = UnitGroups::findOrFail($input['group_id']);
     if (array_key_exists('default', $input)) {
         DB::table('units')->where(['default' => 1, 'group_id' => $input['group_id']])->update(['default' => 0]);
         $input['default'] = 1;
         Units::create($input);
         Helper::add(DB::getPdo()->lastInsertId(), 'added new unit ' . $input['title'] . ' (ID ' . DB::getPdo()->lastInsertId() . ')');
         Helper::add(DB::getPdo()->lastInsertId(), 'changed default unit to ' . $input['title'] . ' (ID ' . DB::getPdo()->lastInsertId() . ') in group ' . $group->title . ' (ID ' . $group->id . ')');
         Units::where(['group_id' => $input['group_id']])->update(['factor' => DB::raw('factor/' . $input['factor'])]);
     } else {
         Units::create($input);
         Helper::add(DB::getPdo()->lastInsertId(), 'added new unit ' . $input['title'] . ' (ID ' . DB::getPdo()->lastInsertId() . ')');
     }
     Session::flash('flash_message', $this->title . ' successfully added!');
     return Redirect::action('UnitsController@index');
 }