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.

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 three columns, avatar_file_name (varchar), avatar_content_type (varchar), and avatar_file_size (integer). 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" 
    end
  end
  down do
    modify_table :users do
      drop_columns :avatar_file_name, :avatar_content_type, :avatar_file_size
    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