restful controller with sensible setup

class PhotosController < ApplicationController
  respond_to :json

  def index
    respond_with load_photos
  end

  def show
    respond_with load_photo
  end

  def new
    respond_with build_photo
  end

  def create
    build_photo
    respond_with save_photo or render json: 'new'
  end

  def edit
    load_photo
    respond_with build_photo
  end

  def update
    load_photo
    build_photo
    respond_with save_photo or render json: 'edit'
  end

  def destroy
    load_photo
    respond_with @photo.destroy
  end

  private

  def load_photos
    @photos ||= photo_scope.to_a
  end

  def load_photo
    @photo ||= photo_scope.find(params[:id])
  end

  def build_photo
    @photo ||= photo_scope.build
    @photo.attributes = photo_params
  end

  def save_photo
    if @photo.save
      redirect_to @photo
    end
  end

  def photo_params
    photo_params = params[:photo]
    photo_params ? photo_params.permit(:caption, :position, :private) : {}
  end

  def photo_scope
    Photo.all
  end

end