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Classier solution for file uploads for Rails, Sinatra and other Ruby web frameworks

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CarrierWave

carrierwave.rubyforge.org

Summary

This plugin for Merb and Rails provides a simple and extremely flexible way to upload files.

Description

Getting Started

Install the latest stable release:

[sudo] gem install carrierwave

In Merb, add it as a dependency to your config/dependencies.rb:

dependency 'carrierwave'

In Rails, add it to your environment.rb:

config.gem "carrierwave"

Quick Start

Start off by generating an uploader:

merb-gen uploader Avatar

or in Rails:

script/generate uploader Avatar

this should give you a file in:

app/uploaders/avatar_uploader.rb

Check out this file for some hints on how you can customize your uploader. It should look something like this:

class AvatarUploader < CarrierWave::Uploader::Base
  storage :file
end

You can use your uploader class to store and retrieve files like this:

uploader = AvatarUploader.new

uploader.store!(my_file)

uploader.retrieve_from_store!('my_file.png')

CarrierWave gives you a store for permanent storage, and a cache for temporary storage. You can use different stores, at the moment a filesystem store, an Amazon S3 store, a Rackspace Cloud Files store, and a store for MongoDB's GridFS are bundled.

Most of the time you are going to want to use CarrierWave together with an ORM. It is quite simple to mount uploaders on columns in your model, so you can simply assign files and get going:

ActiveRecord, DataMapper, Sequel, Mongoid

Make sure you are loading CarrierWave after loading your ORM, otherwise you'll need to require the relevant extension manually, e.g.:

require 'carrierwave/orm/activerecord'

Add a string column to the model you want to mount the uploader on:

add_column :user, :avatar, :string

Open your model file and mount the uploader:

class User
  mount_uploader :avatar, AvatarUploader
end

This works the same with all supported ORMs.

Now you can cache files by assigning them to the attribute, they will automatically be stored when the record is saved.

u = User.new
u.avatar = params[:file]
u.avatar = File.open('somewhere')
u.save!
u.avatar.url # => '/url/to/file.png'
u.avatar.current_path # => 'path/to/file.png'

Changing the storage directory

In order to change where uploaded files are put, just override the store_dir method:

class MyUploader < CarrierWave::Uploader::Base
  def store_dir
    'public/my/upload/directory'
  end
end

This works for the file storage as well as Amazon S3 and Rackspace Cloud Files. Define store_dir as nil if you'd like to store files at the root level.

Securing uploads

Certain file might be dangerous if uploaded to the wrong location, such as php files or other script files. CarrierWave allows you to specify a white-list of allowed extensions.

If you're mounting the uploader, uploading a file with the wrong extension will make the record invalid instead. Otherwise, an error is raised.

class MyUploader < CarrierWave::Uploader::Base
  def extension_white_list
    %w(jpg jpeg gif png)
  end
end

Adding versions

Often you'll want to add different versions of the same file. The classic example is image thumbnails. There is built in support for this:

class MyUploader < CarrierWave::Uploader::Base
  include CarrierWave::RMagick

  process :resize_to_fit => [800, 800]

  version :thumb do
    process :resize_to_fill => [200,200]
  end

end

When this uploader is used, an uploaded image would be scaled to be no larger than 800 by 800 pixels. A version called thumb is then created, which is scaled and cropped to exactly 200 by 200 pixels. The uploader could be used like this:

uploader = AvatarUploader.new
uploader.store!(my_file)                              # size: 1024x768

uploader.url # => '/url/to/my_file.png'               # size: 800x600
uploader.thumb.url # => '/url/to/thumb_my_file.png'   # size: 200x200

One important thing to remember is that process is called before versions are created. This can cut down on processing cost.

It is possible to nest versions within versions:

class MyUploader < CarrierWave::Uploader::Base

  version :animal do
    version :human
    version :monkey
    version :llama
  end
end

Making uploads work across form redisplays

Often you'll notice that uploaded files disappear when a validation fails. CarrierWave has a feature that makes it easy to remember the uploaded file even in that case. Suppose your user model has an uploader mounted on avatar file, just add a hidden field called avatar_cache. In Rails, this would look like this:

<% form_for @user, :html => {:multipart => true} do |f| %>
  <p>
    <label>My Avatar</label>
    <%= f.file_field :avatar %>
    <%= f.hidden_field :avatar_cache %>
  </p>
<% end %>

It might be a good idea to show the user that a file has been uploaded, in the case of images, a small thumbnail would be a good indicator:

<% form_for @user, :html => {:multipart => true} do |f| %>
  <p>
    <label>My Avatar</label>
    <%= image_tag(@user.avatar_url) if @user.avatar? %>
    <%= f.file_field :avatar %>
    <%= f.hidden_field :avatar_cache %>
  </p>
<% end %>

Removing uploaded files

If you want to remove a previously uploaded file on a mounted uploader, you can easily add a checkbox to the form which will remove the file when checked.

<% form_for @user, :html => {:multipart => true} do |f| %>
  <p>
    <label>My Avatar</label>
    <%= image_tag(@user.avatar_url) if @user.avatar? %>
    <%= f.file_field :avatar %>
  </p>

  <p>
    <label>
      <%= f.check_box :remove_avatar %>
      Remove avatar
    </label>
  </p>
<% end %>

If you want to remove the file manually, you can call remove_avatar!.

Uploading files from a remote location

Your users may find it convenient to upload a file from a location on the Internet via a URL. CarrierWave makes this simple, just add the appropriate column to your form and you're good to go:

<% form_for @user, :html => {:multipart => true} do |f| %>
  <p>
    <label>My Avatar URL:</label>
    <%= image_tag(@user.avatar_url) if @user.avatar? %>
    <%= f.text_field :remote_avatar_url %>
  </p>
<% end %>

Providing a default URL

In many cases, especially when working with images, it might be a good idea to provide a default url, a fallback in case no file has been uploaded. You can do this easily by overriding the default_url method in your uploader:

class MyUploader < CarrierWave::Uploader::Base
  def default_url
    "/images/fallback/" + [version_name, "default.png"].compact.join('_')
  end
end

Recreating versions

You might come to a situation where you want to retroactively change a version or add a new one. You can use the recreate_versions! method to recreate the versions from the base file. This uses a naive approach which will reupload and process all versions.

instance = MyUploader.new
instance.recreate_versions!

Or on a mounted uploader:

User.all.each do |user|
  user.avatar.recreate_versions!
end

Configuring CarrierWave

CarrierWave has a broad range of configuration options, which you can configure, both globally and on a per-uploader basis:

CarrierWave.configure do |config|
  config.permissions = 0666
  config.storage = :s3
end

Or alternatively:

class AvatarUploader < CarrierWave::Uploader::Base
  permissions 0777
end

Testing CarrierWave

It's a good idea to test you uploaders in isolation. In order to speed up your tests, it's recommended to switch off processing in your tests, and to use the file storage. In Rails you could do that by adding an initializer with:

if Rails.env.test?
  CarrierWave.configure do |config|
    config.storage = :file
    config.enable_processing = false
  end
end

If you need to test your processing, you should test it in isolation, and enable processing only for those tests that need it.

CarrierWave comes with some RSpec matchers which you may find useful:

require 'carrierwave/test/matchers'

describe MyUploader do
  before do
    MyUploader.enable_processing = true
    @uploader = MyUploader.new(@user, :avatar)
    @uploader.store!(File.open(path_to_file))
  end

  after do
    MyUploader.enable_processing = false
  end

  context 'the thumb version' do
    it "should scale down a landscape image to be exactly 64 by 64 pixels" do
      @uploader.thumb.should have_dimensions(200, 200)
    end
  end

  context 'the small version' do
    it "should scale down a landscape image to fit within 200 by 200 pixels" do
      @uploader.small.should be_no_larger_than(200, 200)
    end
  end

  it "should make the image readable only to the owner and not executable" do
    @uploader.should have_premissions(0600)
  end
end

Using Amazon S3

Older versions of CarrierWave used the aws-s3 and right_aws libraries. The Aws is now used meaning european buckets are supported out the box. Ensure you have it installed:

gem install aws

You'll need to configure a bucket, access id and secret key like this:

CarrierWave.configure do |config|
  config.s3_access_key_id = 'xxxxxx'
  config.s3_secret_access_key = 'xxxxxx'
  config.s3_bucket = 'name_of_bucket'
end

Do this in an initializer in Rails, and in a before_app_loads block in Merb.

And then in your uploader, set the storage to :s3

class AvatarUploader < CarrierWave::Uploader::Base
  storage :s3
end

That's it! You can still use the CarrierWave::Uploader#url method to return the url to the file on Amazon S3.

Using Rackspace Cloud Files

Cloud Files support requires a Rackspace Cloud username and API key. You must also create a container for Carrierwave to use, and mark it public (publish it to the CDN)

CarrierWave.configure do |config|
  config.cloud_files_username = 'xxxxxx'
  config.cloud_files_api_key = 'xxxxxxxxxxxxxxxxxxxxx'
  config.cloud_files_container = 'name_of_bucket'
end

You can optionally include your CDN host name in the configuration. This is highly recommended, as without it every request requires a lookup of this information.

config.cloud_files_cdn_host = "c000000.cdn.rackspacecloud.com"

Do this in an initializer in Rails, and in a before_app_loads block in Merb.

And then in your uploader, set the storage to :cloud_files

class AvatarUploader < CarrierWave::Uploader::Base
  storage :cloud_files
end

That's it! You can still use the CarrierWave::Uploader#url method to return the url to the file on the Cloud Files CDN.

Using MongoDB's GridFS store

You'll need to configure the database and host to use:

CarrierWave.configure do |config|
  config.grid_fs_database = 'my_mongo_database'
  config.grid_fs_host = 'mongo.example.com'
end

The defaults are 'carrierwave' and 'localhost'.

And then in your uploader, set the storage to :grid_fs:

class AvatarUploader < CarrierWave::Uploader::Base
  storage :grid_fs
end

Since GridFS doesn't make the files available via HTTP, you'll need to stream them yourself. In Rails for example, you could use the send_data method. You can tell CarrierWave the URL you will serve your images from, allowing it to generate the correct URL, by setting eg:

CarrierWave.configure do |config|
  config.grid_fs_access_url = "/image/show"
end

Using RMagick

If you're uploading images, you'll probably want to manipulate them in some way, you might want to create thumbnail images for example. CarrierWave comes with a small library to make manipulating images with RMagick easier, you'll need to include it in your Uploader:

class AvatarUploader < CarrierWave::Uploader::Base
  include CarrierWave::RMagick
end

The RMagick module gives you a few methods, like CarrierWave::RMagick#resize_to_fill which manipulate the image file in some way. You can set a process callback, which will call that method any time a file is uploaded.

class AvatarUploader < CarrierWave::Uploader::Base
  include CarrierWave::RMagick

  process :resize_to_fill => [200, 200]
  process :convert => 'png'

  def filename
    super + '.png'
  end
end

Check out the manipulate! method, which makes it easy for you to write your own manipulation methods.

Using ImageScience

ImageScience works the same way as RMagick.

class AvatarUploader < CarrierWave::Uploader::Base
  include CarrierWave::ImageScience

  process :resize_to_fill => [200, 200]
end

Using MiniMagick

MiniMagick is similar to RMagick but performs all the operations using the 'mogrify' command which is part of the standard ImageMagick kit. This allows you to have the power of ImageMagick without having to worry about installing all the RMagick libraries.

See the MiniMagick site for more details:

github.com/probablycorey/mini_magick

And the ImageMagick command line options for more for whats on offer:

www.imagemagick.org/script/command-line-options.php

Currently, the MiniMagick carrierwave processor provides exactly the same methods as for the RMagick processor.

class AvatarUploader < CarrierWave::Uploader::Base
  include CarrierWave::MiniMagick

  process :resize_to_fill => [200, 200]
end

Migrating

If you are using Paperclip, you can use the provided compatibility module:

class AvatarUploader < CarrierWave::Uploader::Base
  include CarrierWave::Compatibility::Paperclip
end

See the documentation for Paperclip::Compatibility::Paperclip for more detaills.

Be sure to use mount_on to specify the correct column:

mount_uploader :avatar, AvatarUploader, :mount_on => :avatar_file_name

Unfortunately AttachmentFoo differs too much in philosophy for there to be a sensible compatibility mode. Patches for migrating from other solutions will be happily accepted.

i18n

The activerecord validations use the Rails i18n framework. Add these keys to your translations file:

carrierwave:
  errors:
    integrity: 'Not an image.'
    processing: 'Cannot resize image.'

Contributors

These people have contributed their time and effort to CarrierWave:

  • Jonas Nicklas

  • Pavel Kunc

  • Andrew Timberlake

  • Durran Jordan

  • Scott Motte

  • Sho Fukamachi

  • Sam Lown

  • Dave Ott

  • Quin Hoxie

    1. Wade Minter

  • Trevor Turk

  • Nicklas Ramhöj

  • Matt Hooks

License

Copyright © 2008 Jonas Nicklas

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Development

If you want to run the tests (and you should) it might be convenient to install the development dependencies, you can do that with:

sudo gem install carrierwave --development

CarrierWave is still young, but most of it is pretty well documented. It is also extensively specced, and there are cucumber features for some common use cases. Just dig in and look at the source for more in-depth explanation of what things are doing.

Issues are reported on GitHub, pull requests are very welcome!

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