Paperclip on Rails 3 — damn easy!

Paperclip is a Rails plug-in for attaching files to models. Using Paperclip is also very easy to use, it can thumbnail your images and also send the files to Amazon S3.

From this link, you can find the steps for creating a Rails project from scratch with paperclip.
http://jameswilding.net/2010/07/24/paperclip-rails-3/

As I have already had a project that needs file attachments, I follow a slightly different path.

The steps for adding a file attachment is as follows:

1. Install Paperclip

$ rails plugin install git://github.com/thoughtbot/paperclip.git

2. Add image attribute to your model

  #paperclip
  has_attached_file :photo,
     :styles => {
       :thumb=> "100x100#",
       :small  => "400x400>" }

3. Create migration file and add the necessary columns to your database

$ rails generate migration add_photo_to_microposts photo_file_name:string photo_content_type:string photo_file_size:integer

rake db:migrate

4. Change you form

<%= form_for @micropost  , :html => { :multipart => true } do |f| %>
  <%= f.file_field :photo %>
  ...

5. Change view that will show the uploaded image (optional)

<% if micropost.photo.exists? then %>
	<%= image_tag micropost.photo.url(:small) %>
<% end %>

That’s it. It is done.