=DataMapper Paperclip

DM-Paperclip is a port of Thoughtbot's Paperclip plugin to work with DataMapper 0.9.  This plugin is fully compatible 
with
the original ActiveRecord-oriented Paperclip.  You could take an existing ActiveRecord database and use it with 
DataMapper.
The module also includes updates validation handling and automatic including of the necessary 'property' fields into
your model.

To use it within your models, you need to ensure the three database fields are included.  They are {name}_file_name,
{name}_content_type, and {name}_file_size.  The first two are strings, the final _file_size column is an integer. So
if your user model has an avatar field, then you would add avatar_file_name, avatar_content_type, and avatar_file_size.

As with the original Paperclip plugin, it allows processing of thumbnails at the time the record is saved though 
ImageMagick.
It processes the thumbnails through the command-line applications instead of using RMagick.

See the documentation for the +has_attached_file+ method for options.

==Code

The code DM-Paperclip is available at Github:

  git clone git://github.com/krobertson/dm-paperclip.git

It is regularly updated to keep in sync with the latest from Thoughtbot.

Releases are tagged within the repository and versioned the same as the original model.  You can also get the latest 
release
packaged as a gem through Rubyforge:

  sudo gem install dm-paperclip

==Usage

In your model:

  class User
    include DataMapper::Resource
    include Paperclip::Resource
    property :id, Integer, :serial => true
    property :username, String
    has_attached_file :avatar,
                      :styles => { :medium => "300x300>",
                                   :thumb => "100x100>" }
  end

Your database will need to add four columns, avatar_file_name (varchar), avatar_content_type (varchar), and
avatar_file_size (integer), and avatar_updated_at (datetime).  You can either add these manually, auto-
migrate, or use the following migration:

  migration( 1, :add_user_paperclip_fields ) do
  up do
      modify_table :users do
        add_column :avatar_file_name, "varchar(255)"
        add_column :avatar_content_type, "varchar(255)"
        add_column :avatar_file_size, "integer"
        add_column :avatar_updated_at, "datetime"
      end
    end
    down do
      modify_table :users do
        drop_columns :avatar_file_name, :avatar_content_type, :avatar_file_size, :avatar_updated_at
      end
    end
  end

In your edit and new views:

  <% form_for @user, { :action => url(:user), :multipart => true } do %>
    <%= file_field :name => 'avatar' %>
  <% end %>

In your controller:

  def create
    ...
    @user.avatar = params[:avatar]
  end

In your show view:

  <%= image_tag @user.avatar.url %>
  <%= image_tag @user.avatar.url(:medium) %>
  <%= image_tag @user.avatar.url(:thumb) %>

The following validations are available:

  validates_attachment_presence :avatar
  validates_attachment_content_type :avatar, :content_type => "image/png"
  validates_attachment_size :avatar, :in => 1..10240
  validates_attachment_thumbnails :avatar

In order to use validations, you must have loaded the 'dm-validations' gem into your app
(available as a part of dm-more).  If the gem isn't loaded before DM-Paperclip is loaded,
the validation methods will be excluded.  You will also need to include DataMapper::Validate
into your mode:

  class User
    include DataMapper::Resource
    include DataMapper::Validate
    include Paperclip::Resource
    property :id, Integer, :serial => true
    property :username, String
    has_attached_file :avatar,
                      :styles => { :medium => "300x300>",
                                   :thumb => "100x100>" }
    validates_attachment_size :avatar, :in => 1..5120
  end