Laravel Null转储值

I need to find the data coresponding to a specific id, i keep getting this error, i tried dump the id value and it shows NULL, no idea why, here is code :

Controller :

 function fetchdata(Request $request)
        {
            $id = $request->get('ID');
            $req = Demo::find($id);
            $output = array(
                'reponse'    =>  $req->reponse,
            );
            echo json_encode($output);
        }

View :

$(document).on('click', '.req_reponse', function(){
        var id = $(this).attr("ID");
        $('#form_output').html('');
        $.ajax({
            url:"{{route('admin.fetchdata')}}",
            method:'get',
            data:{id:id},
            dataType:'json',
            success:function(data)
            {
                $('#reponse').val(data.reponse);
                $('#ID').val(id);
                $('#studentModal').modal('show');
            }
        })
    });

Error :

'reponse'    =>  $req->reponse,

    "Trying to get property of non-object"

Getting error because there is no key like reponse in $req variable.

I think this should work fine:

$id = $request->ID;
$demo = Demo::find($id);
if (empty($demo)) {
    exit(json_encode(['message' => "not found"])); // Or any thing you want to return if record not found corresponding to given id.
}
$output = array(
    'reponse' => $demo->reponse,
);
echo json_encode($output);
exit;

Eloquent doesn't provide such a key response. Please try the below script.

 function fetchdata(Request $request)
            {
                $id = $request->get('ID');
                $req = Demo::find($id);
                $output = array(
                    'reponse'    =>  $req->your_column_name,
                );
                echo json_encode($output);
                exit;
            }