Install and read https://github.com/thoughtbot/paperclip and https://github.com/thoughtbot/paperclip/wiki/Thumbnail-Generation first.

$ rails generate paperclip product asset

Automatically detected.

Considering a has_attached_file :asset declaration, all :asset_file_name, :asset_content_type.. columns will be hidden. A file upload field will be created and accessible for customization in the DSL: field :asset, :paperclip.

One thing you may need is a delete method in your model. Paperclip does not include it, you'll need to add it manually. RailsAdmin will detect it and add a checkbox.

class Product < ActiveRecord::Base has_attached_file :asset, :styles => { :thumb => "100x100#", :small => "150x150>", :medium => "200x200" } validates_attachment_content_type :asset, :content_type => /\Aimage\/.*\Z/ # add a delete_<asset_name> method:  attr_accessor :delete_asset before_validation { self.asset.clear if self.delete_asset == '1' } end

If you use a attr_accessible strategy, don't forget to add delete_asset to the whitelist.

More here