Ruby on rails 3 - 在form_for中使用checkbox字段，在ajax调用中发送html和json请求，它应该是js或json

I have toggle button on my form and on toggling it i am sending ajax call request to save updated boolean value in the database from controller. but it is sending Html and json request both. I just want to send only one json request. (using rails 3.*)I have toggle button on my form and on toggling