使用SILEX获取PUT路由中的数据

Get data incoming using $request->get('bar') in routes PUT using SILEX

$app->put('foo/{id}', function(Request $request, $id) use ($app){
  return var_dump($request->get('bar')); //return null 
});

Why return null? How do I access data?

You are getting null because var_dump returns null. var_dump prints the content of the variable to screen, but does not return it. You may be looking for var_export.