Paperclip has_attached_file not working with Rails establish_connection -

i trying access images paperclip using establish_connection.
here code of model article.rb

class article < activerecord::base    if rails.env.production?     establish_connection secondary_db_config   else     establish_connection "article_#{rails.env}"   end      has_many :assets, dependent: :destroy      accepts_nested_attributes_for :assets     validates_associated :assets end 

file asset.rb

class asset < activerecord::base    if rails.env.production?     establish_connection secondary_db_config   else     establish_connection "article_#{rails.env}"   end    belongs_to :article, polymorphic: true     has_attached_file :image, :styles => { :large=> "1200x700",:medium => "800x" }    validates_attachment_content_type :image, :content_type => ["image/jpg", "image/png", "image/jpeg"] end 

and code in view

<% article.all.each |article| %>     <div class="project-item col-sm-6 col-md-4 col-lg-3">         <% if article.assets.length > 0 %>             <img src="<%= article.assets.last.image.url(:medium) %>" alt="<%=article.name%>" />         <% end %>         <div class="hover-title">             <h2 class="project-title"><%= article.name%></h2>             <p><%= property.short_desc %></p>         </div>     </div> <% end %> 

it throws error this

undefined method `has_attached_file' asset (call 'asset.connection' establish connection):class

you need install paperclip gem in existing project, copy , configure aws s3 information project need access.
in gemfile

# paperclip gem image manipulation gem 'paperclip', :git=> 'https://github.com/thoughtbot/paperclip', :ref => '523bd46c768226893f23889079a7aa9c73b57d68'  # aws sdk uploading @ aws gem 'aws-sdk', '< 2.0' gem 's3' 

in production.rb

# configuration amazon s3   config.paperclip_defaults = {     :storage => :s3,     :s3_region=> env['aws_region'],     :s3_credentials => {       :bucket => env['aws_bucket'],       :access_key_id => env['aws_access_key_id'],       :secret_access_key => env['aws_secret_access_key']     }   }