Building a Pivot Grid and handling jqGrid $app is undefined

[vishok]

Following the tutorial "Building a Pivot Grid and handling jqGrid" i get an error. Laravel say to me $app is undefined. The piece of code that generate the problem is this :
Route::post('/invoice-item-grid', function() use ($app)
{
GridEncoder::encodeRequestedData(new InvoiceItemRepository($app['db']), Input::all());
});