block-json-xml.rb

# before, would depend on routing constraints to block .json/.xml as 404 not found
class ThingyController < ApplicationController

  def show
    @thingy = Thingy.find params[:id]
  end

  def update
    @thingy = Thingy.find params[:id]

    if @thingy.update_attributes(params[:thingy])
      redirect_to thingy_path, notice: "Your Thingy was successfully updated."
    else
      render :show
    end
  end

end

# after, uses respond_to and respond_with to respond with 406 unacceptable
class ThingyController < ApplicationController

  respond_to :html

  def show
    @thingy = Thingy.find params[:id]
    respond_with(@thingy)
  end

  def update
    @thingy = Thingy.find params[:id]
    @thingy.update_attributes(params[:thingy])
    respond_with(@thingy)
  end

end