Adrift¶ ↑

Adrift is a DIY library to ease attaching files to a model by making them behave just like any other attribute.

It currently works only with ActiveRecord and DataMapper within Rails or Sinatra, but it should be pretty adaptable to another environment.

Installation¶ ↑

Install it as any other gem:

$ gem install adrift

Or, if you are using Bundler, put the following in your Gemfile:

gem 'adrift'

If you want to create thumbnails, you’ll also need to install ImageMagick.

Usage¶ ↑

The easiest way to use Adrift is to call attachment in your model class definition after you require it as follows:

# remember to require your ORM library before Adrift
require 'adrift'
require 'adrift/integration'

See the attachment documentation in the module named after you ORM library located under Adrift::Integration (for instance, Adrift::Integration::DataMapper#attachment for DataMapper). This method allow to configure the behaviour of the Attachment it defines. However, if your attachments share a lot of configuration you can (and probably should!) change the default options with Adrift::Attachment.config.

Adrift only allows to store the attached files in the filesystem and provides a simple wrapper around ImageMagick to create thumbnails. If you have different needs you can provide your own storage (who handles saving and removing the attached files) and/or processor (who handles handles transforming the attached files or creating new ones from them) objects like this:

# for every Attachment object
Adrift::Attachment.config do
  storage:   Proc.new { MyOwnStorage.new },
  processor: Proc.new { MyOwnProcessor.new }
end

# just for this one
Adrift::Attachment.new :avatar,
  storage:   Proc.new { MyOwnStorage.new },
  processor: Proc.new { MyOwnProcessor.new }

See the Adrift::Storage and Adrift::Processor documentation for the interface your storage and processor objects need to satisfy. Additionally, you can take a look at Adrift::Storage::Filesystem and Adrift::Processor::Thumbnail for example implementations.

Getting started with Sinatra and DataMapper¶ ↑

In app.rb:

require 'sinatra'
require 'dm-core'
require 'dm-migrations'

# require Adrift after DataMapper
require 'adrift'
require 'adrift/integration'

DataMapper.setup(:default, "sqlite3://#{settings.root}/development.sqlite3")

class User
  include DataMapper::Resource

  property :id,              Serial
  property :name,            String
  property :avatar_filename, String

  # when defining attachments, beware that a String property to
  # store the attached file's name is needed for every one.
  # this property is named after the attachment, in this case,
  # :avatar_filename after :avatar.
  attachment :avatar, styles: { thumb: '50x50' }
end

DataMapper.finalize
DataMapper.auto_migrate!

get '/users' do
  @users = User.all
  erb :users
end

get '/users/new' do
  @user = User.new
  erb :new_user
end

post '/users' do
  @user = User.create(params[:user])
  redirect '/users'
end

In views/users.erb:

<ul>
  <% @users.each do |user| %>
    <li>
      <a href="<%= user.avatar.url %>">
        <img src="<%= user.avatar.url(:thumb) %>" alt="<%= user.name %>" />
      </a>
    </li>
  <% end %>
</ul>

In views/new_user.erb:

<form action="/users" method="post" enctype="multipart/form-data">
  <label for="user_name">Name</label>
  <input type="text" id="user_name" name="user[name]" />

  <label for="user_avatar">Avatar</label>
  <input type="file" id="user_avatar" name="user[avatar]" />

  <input type="submit" />
</form>

Getting started with Rails and ActiveRecord¶ ↑

Create a new application, add the gem to the Gemfile and then run:

$ script/rails generate scaffold user name:string avatar_filename:string
$ rake db:migrate

Then, modify app/models/user.rb to look like:

class User < ActiveRecord::Base
  # when defining attachments, beware that a string column to
  # store the attached file's name is needed for every one.
  # this property is named after the attachment, in this case,
  # :avatar_filename after :avatar.
  attachment :avatar, styles: { thumb: '50x50' }
end

And app/controllers/users_controller.rb:

class UsersController < ApplicationController
  def index
    @users = User.all
  end

  def new
    @user = User.new
  end

  def create
    @user = User.create(params[:user])
    redirect_to users_url
  end
end

And app/views/users/index.html.erb:

<ul>
  <% @users.each do |user| %>
    <li>
      <%= link_to(
            image_tag(user.avatar.url(:thumb), alt: user.name),
            user.avatar.url
          ) %>
    </li>
  <% end %>
</ul>

And app/views/users/_form.html.erb:

<%= form_for(@user, html: { multipart: true }) do |f| %>
  <%= f.label :name %>
  <%= f.text_field :name %>
  <%= f.label :avatar %>
  <%= f.file_field :avatar %>
  <%= f.submit %>
<% end %>

License¶ ↑

Adrift is released under MIT license. See LICENSE.