Active administrator with carrier

Question

I am using an active administrator with a carrier wave. I am encountering a problem downloading an image using an active admin. I already have an image in my folder public/imgnamed banner.png. Now I want to override this image with another image through the admin panel. When I upload the image, it shows me the options as shown below:

Parameters: {"utf8"=>"✓", "authenticity_token"=>"iHI02QCklnooY2WvKOAI/OUPi6phmvVsYnXuRzvXg2Q=", "home_banner"=>{"home_banner_image"=>{"image"=>#<ActionDispatch::Http::UploadedFile:0xd8f728c @original_filename="Penguins.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"home_banner[home_banner_image][image]\"; filename=\"Penguins.jpg\"\r\nContent-Type: image/jpeg\r\n", @tempfile=#<File:/tmp/RackMultipart20140612-18313-18qw3aj>>}}, "commit"=>"Update Home banner", "id"=>"539981982131fc9c0e000002"}

But it does not save the image in the database.

Here is my model and bootloader

model: -

class Banner
 include Mongoid::Document
 include Mongoid::Timestamps::Created
 include Rails.application.routes.url_helpers

 field :banner_image, type: String
 mount_uploader :banner_image, BannerUploader
end

Uploader: -

require 'open-uri'
require "digest/md5"
require 'carrierwave/processing/mini_magick'
class BannerUploader < CarrierWave::Uploader::Base

 storage :file

 def store_dir
  # "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  "/public/img"
 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
  "banner.png" if original_filename
 end

end

And my activeadmin for admin folder: -

ActiveAdmin.register Banner do

 index do                            
  column :banner_image                              
  default_actions                   
 end 

 form(:html => { :multipart => true }) do |f|
  f.inputs "Banner Image" do
   f.semantic_fields_for :banner_image do |fi|
    fi.input :image, :as => :file
   end
  end
  f.buttons
 end 
end

I am using mongoDb, and my requirement is that I already have the image in the / img public folder to update it via admin so that it automatically reflects on the front side without changing the view code.

, . .

Answer 1

, :

ActiveAdmin 0.6 1.0 ~ Okt./Nov. 2014

f.input :header_image, :as => :file, :hint => f.template.image_tag(f.object.image.url(:thumb))

ActiveAdmin 1.0 ~ Okt./Nov. 2014

f.input :header_image, :as => :file, :hint => image_tag(object.image.url(:thumb))