jquery autocomplete和laravel 5.1抛出内部服务器错误500

I'km trying the autocomplete by selecting data from DB and getting back the response as json but all I got is internal server error, could it be a problem of csrf token?

this is the script

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script>
    <script src="http://code.jquery.com/ui/1.11.4/jquery-ui.js" ></script>
    <script type="text/javascript">
        $(document).ready(function () {
            $('input:text').bind({

            });
            $("#auto").autocomplete({
                minLength:2,
                source: '{{ URL('getdata') }}'

            });
        });
    </script>

and this in the controller:

public function getData(){

            $term = Input::get('term');

            $data = DB::table('items')->distinct()->select('item_name')->where('word', 'LIKE', $term.'%')->groupBy('word')->take(10)->get();
            foreach ($data as $v) {
                $return_array[] = array('value' => $v->word);
            }

            return Response::json($return_array);


    }

Problem was in getData function, this one works.

public function getData(){

            $term = Input::get('term');

            $data = DB::table('items')->distinct()->select('item_name')->where('item_name', 'LIKE', $term.'%')->groupBy('item_name')->take(10)->get();
            foreach ($data as $v) {
                $return_array[] = array('value' => $v->item_name);
            }

            return Response::json($return_array);


    }