我怎样才能在ajax中设计返回JSON：成功调用而不是HTML

I am trying to set up my devise registration as an ajax call, so that I can get the errors in my user sign up flow. Currently, I have it so that it is able to create a user on success, but I am unable to get the errors in JSON form to use properly to make validations for the user.I am trying to set up my devise registration as