Rails Paperclip S3 Example/Tutorial

An easy guide to image attachments using paperclip and Amazon Simple Storage Service (Amazon S3). Includes example files.

Prerequisites

• Imagemagick and the RMagick gem both need to be installed and configured for your system.
• If you want to use the local file system for storage, you can skip the next three prerequisites and use the alternate code in /models/user.rb.
• You need to sign up with Amazon Simple Storage Service
• Amazon will provide you with the necessary security credentials: access_key_id and secret_access_key.
• You need to set up an amazon bucket for your storage.

Get Started

This tutorial assumes that you are setting up attachments on your user model.
You can alter it to attach images to any model you like.

Add these lines to /config/environment.rb

config.gem "paperclip", :version => "~> 2.3"
config.gem "aws-s3", :version => ">= 0.6.2", :lib => "aws/s3"  (ignore if you are using local storage).
require 'RMagick' (at the very end of environment.rb)

rake gems:install

Generate a migration:

script/generate paperclip user avatar ( User is the model and avatar is the attachment name )

rake db:migrate

Set up your user model: — S3 storage

attr_accessible :avatar, :avatar_file_name	
validates_attachment_presence :avatar - leave out to use optional default images
validates_attachment_size :avatar, :less_than => 3.megabytes    	

has_attached_file :avatar,
:styles => {:thumb => {:geometry => '75x75>', :format => :jpg},
:original => {:geometry => '180x180>', :format => :jpg}},
:storage => :s3,
:s3_credentials => "#{RAILS_ROOT}/config/s3.yml",
:path => ":attachment/:id/:style.:extension",
:bucket => 'Your Amazon S3 Bucket Name',
:default_url => '/images/missing_:style.jpg'

Or, set up your user model: — local storage

attr_accessible :avatar, :avatar_file_name
validates_attachment_presence :avatar - leave out to use optional default images
validates_attachment_size :avatar, :less_than => 3.megabytes

_attached_file :avatar,
:styles => {:thumb => {:geometry => '75x75>', :format => :jpg},
:original => {:geometry => '180x180>', :format => :jpg}},
:url => "/system/:attachment/:id/:style/:basename.:extension",  
:path => ":rails_root/public/system/:attachment/:id/:style/:basename.:extension",  
:default_url => '/images/missing_:style.jpg'   

You can set up as many styles/sizes/formats as you need:

medium => {:geometry => '100x100>', :format => :png}
giant => {:geometry => '600x800>', :format => :png}

The '>' symbol keeps the image from being modified when resizing, using a '#' symbol will centrally
crop the image. If you use original as one of your style names, the uploaded file will be resized. 
If you do not use this style, the original will be kept in the file system.

Add default images to  /public/images   named missing_style.format for every style you create.
If no image is attached, paperclip will use these images. I have included some nice default photos of
bananas in the example files for your convenience.

Example default image names:
missing_original.jpg
missing_thumb.jpg
missing_giant.png

Create a new file in /config , name it s3.yml and add the following from your Amazon account credenteals:

access_key_id: Your Access Key Id
secret_access_key: Your Secret Access Key 

Create a new file in /config/initializers, name it paperclip.rb and add the following:

require "paperclip"  
Paperclip.options[:command_path] = "/ImageMagick"

The views

user/new.html.erb

<% form_for (@user, :html => { :multipart => true}) do |f| %>
<%= f.error_messages %>
<%= f.label :avatar, 'Choose a photo:'%>
<%= f.file_field :avatar %>  
<%= f.submit 'Create' %>
<% end %>

user/show.html.erb

The original style:
<%=h image_tag @user.avatar.url %> 
The thumbnail style:     
<%=h image_tag @user.avatar.url(:thumb) %>	

Fire up your server and test everything out.

Related Links

• Thoughtbot paperclip
• More paperclip documentation
• Amazon web services
• Imagemagick / RMagick
• Railscasts – another good tutorial on Paperclip