Ruby on Rails Paperclip tutorial - rails 4.0.3, Ruby 2.1, Paperclip 4.1.1

Step 1, New a project
rails new demo

Step 2, Update Gemfile
add paperclip, mysql2 gem, enable JavaScript runtime
gem 'mysql2'
gem 'paperclip'
gem 'therubyracer', platforms: :ruby // remove the comment


You should be able to run rails server now:
ang@ubuntuChef:/opt/ruby/demo$ rails server
=> Booting WEBrick
=> Rails 4.0.3 application starting in development on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
[2014-02-27 18:39:15] INFO  WEBrick 1.3.1
[2014-02-27 18:39:15] INFO  ruby 2.1.1 (2014-02-24) [x86_64-linux]
[2014-02-27 18:39:15] INFO  WEBrick::HTTPServer#start: pid=3187 port=3000

Step 3, Creating the Database

ang@ubuntuChef:/opt/ruby/demo$ rails generate scaffold User username:string

Your migration file looks like:
ang@ubuntuChef:/opt/ruby/demo$ less db/migrate/20140227235934_create_users.rb

class CreateUsers < ActiveRecord::Migration
  def change
    create_table :users do |t|
      t.string :username

      t.timestamps
    end
  end
end

add paperclip  - one is image, one is zip file


ang@ubuntuChef:/opt/ruby/demo$ rails generate paperclip User avator download

ang@ubuntuChef:/opt/ruby/demo$ vim db/migrate/20140228000158_add_attachment_avator_download_to_users.rb

class AddAttachmentAvatorDownloadToUsers < ActiveRecord::Migration
  def self.up
    change_table :users do |t|
      t.attachment :avator
      t.attachment :download
    end
  end

  def self.down
    drop_attached_file :users, :avator
    drop_attached_file :users, :download
  end
end
 
Step 4, Applying the Migration - there are two migrations.

ang@ubuntuChef:/opt/ruby/demo$ rake db:migrate
==  CreateUsers: migrating ====================================================
-- create_table(:users)
   -> 0.0196s
==  CreateUsers: migrated (0.0199s) ===========================================

==  AddAttachmentAvatorDownloadToUsers: migrating =============================
-- change_table(:users)
   -> 0.2719s
==  AddAttachmentAvatorDownloadToUsers: migrated (0.2721s) ====================

Step 5, Start server
http://192.168.88.216:3000/users/new

You will see the new user page, but no file upload options. We need to add them manually.

Step 6, update model
ang@ubuntuChef:/opt/ruby/demo$ vim app/models/user.rb

class User < ActiveRecord::Base
  has_attached_file :avator
  has_attached_file :download
  validates_attachment_content_type :avator, :content_type => %w(image/jpeg image/jpg image/png application/pdf)
  validates_attachment_content_type :download, :content_type => %w(application/octet-stream  application/x-zip application/x-zip-compressed application/pdf application/x-pdf)
end



Step 7, update view
ang@ubuntuChef:/opt/ruby/demo$ vim app/views/users/_form.html.erb



  <div class="field">
    <%= f.label :avator %><br>
    <%= f.file_field :avator %>
  </div>
  <div class="field">
    <%= f.label :download %><br>
    <%= f.file_field :download %>
  </div>







ang@ubuntuChef:/opt/ruby/demo$ vim app/views/users/show.html.erb

<p>
  <strong>Avator:</strong>
 <%= image_tag @user.avator.url %>
<%= image_tag @user.avator.url(:thumb) %>
</p>
<p>
  <strong>Download:</strong>
  <a href="<%= @user.download.url %>" > Download File </a>
</p>




Step 8, update controller
ang@ubuntuChef:/opt/ruby/demo$ vim app/controllers/users_controller.rb

    def user_params
      params.require(:user).permit(:username, :avator , :download)
    end





Step 9
Run server:
ang@ubuntuChef:/opt/ruby/demo$ rails server