cant see the aws-s3 url saved in rails database

I have successfully implemented image uploading using carrierwave, fog and Amazon S3. In my imageuploader am using only fog as storage. But when i check my database i can see that just the file name is written instead of the amazon url. In my views its fetching correctly from aws without any issues.

Is it supposed to be like this? If so how the application figure out the exact url to s3?

imageuploader.rb`

    # encoding: utf-8

class ImageUploader < CarrierWave::Uploader::Base

  # Include RMagick or MiniMagick support:
  # include CarrierWave::RMagick
  # include CarrierWave::MiniMagick
  include CarrierWave::MiniMagick

  #Include the sprockets-rails helper  for Rails 4+ compatibility:
  include Sprockets::Rails::Helper

  # Choose what kind of storage to use for this uploader:
  #storage :file
  storage :fog

  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:

  # Provide a default URL as a default if there hasn't been a file uploaded:
  # def default_url
  #   # For Rails 3.1+ asset pipeline compatibility:
  #   # ActionController::Base.helpers.asset_path("fallback/" + [version_name, "default.png"].compact.join('_'))
  #
  #   "/images/fallback/" + [version_name, "default.png"].compact.join('_')

  # end





  # Process files as they are uploaded:
  # process :scale => [200, 300]
  #
  # def scale(width, height)
  #   # do something
  # end

  # Create different versions of your uploaded files:
  # version :thumb do
  #   process :resize_to_fit => [50, 50]
  # end

  version :index_size do
    process :resize_to_fill => [258, 173]
  end

  version :thumb_size do
    process :resize_to_fill => [100, 100]
  end



  # Add a white list of extensions which are allowed to be uploaded.
  # For images you might use something like this:
  # def extension_white_list
  #   %w(jpg jpeg gif png)
  # end

  def extension_white_list
     %w(jpg jpeg gif png)
  end

  # Override the filename of the uploaded files:
  # Avoid using model.id or version_name here, see uploader/store.rb for details.
  # def filename
  #   "something.jpg" if original_filename
  # end

end

models

class Picture < ActiveRecord::Base

  belongs_to :listing

  mount_uploader :image, ImageUploader

end

class Listing < ActiveRecord::Base

  belongs_to :user

  has_many :amenityconnecters
  has_many :amenities, through:  :amenityconnecters

  has_many :pictures, :dependent => :destroy

  accepts_nested_attributes_for :pictures, \
    reject_if: proc{ |param| param[:image].blank? && param[:image_cache].blank? && param[:id].blank? }, \
    allow_destroy: true

end

controllers

class ListingsController < ApplicationController
  before_action :set_listing, only: [:show, :edit, :update, :destroy]


  def new
  @listing= Listing.new
  end

  def create
    @listing=Listing.new(listing_params)
    @listing.user_id=current_user.id

    if @listing.save
      render 'edit', notice: "Successfully created new listing"
    else
      render 'new'
      end
  end

  def show

  end

  def index
   @listings = Listing.all
  end

  def edit

  end

  def update

    if @listing.update(listing_params)
      flash[:success] = "Your listing was updated successfully"
      redirect_to listing_path(@listing)
    else
      render 'edit'
    end
  end


  private

  def set_listing
   @listing = Listing.find(params[:id])
  end

  def listing_params
  params.require(:listing).permit(:title, :description, pictures_attributes: [:id, :image, :image_cache, :_destroy],:amenity_ids => [])
  end



end