fabrinal

def update
    respond_to do |format|
      if @photo_gallery.update(photo_gallery_params)
         # add compare method in here
        compare_photos(params[:photos])
        format.html { redirect_to @photo_gallery, notice: 'Photo gallery was successfully updated.' }
        format.json { render :show, status: :ok, location: @photo_gallery }
      else
        format.html { render :edit }
        format.json { render json: @photo_gallery.errors, status: :unprocessable_entity }

fabrinal

def create
    @photo_gallery = PhotoGallery.new(photo_gallery_params)
    respond_to do |format|
      if @photo_gallery.save
        # add save photos method in here
        save_photos(params[:photos])
        format.html { redirect_to @photo_gallery, notice: 'Photo gallery was successfully created.' }
        format.json { render :show, status: :created, location: @photo_gallery }
      else
        format.html { render :new }

fabrinal

private
    # Use callbacks to share common setup or constraints between actions.
    def set_photo_gallery
      @photo_gallery = PhotoGallery.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def photo_gallery_params
      # add :photos param below
      params.require(:photo_gallery).permit(:description,:photos)

fabrinal

class Photo < ActiveRecord::Base
  belongs_to :photo_gallery
  has_attached_file :image, :styles => { 
  	:medium => "300x300>", 
	:thumb => "100x100>" 
	}, 
  :path => ":rails_root/app/assets/images/photos/:style/:filename"
  validates_attachment_content_type :image, :content_type => /\Aimage\/.*\Z/
end