Ruby to_json :methods arguments

I am using the to_json method on an object, and trying to get the :methods argument to work. I have a method on my model (Drop) called is_favorited_by_user?. This method takes an argument of the current_user, and then checks to see if the drop is favorited by the user. How can I pass this argument through the to_json method.

render :json => @drops.to_json(:methods => :is_favorited_by_user?(current_user))

You can add current_user attribute to your model and set it before executing to_json

  attr_accessor :current_user

  def is_favorited_by_user?(user=nil)
    user ||= current_user
    # rest of your code
  end


@drops.current_user = current_user
render :json => @drops.to_json(:methods => :is_favorited_by_user?)