carrierwave

Created: 2008-08-28 18:39
Updated: 2019-02-28 11:32

README.md

CarrierWave

This gem provides a simple and extremely flexible way to upload files from Ruby applications. It works well with Rack based web applications, such as Ruby on Rails.

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Information

Getting Help

  • Please ask the community on Stack Overflow for help if you have any questions. Please do not post usage questions on the issue tracker.
  • Please report bugs on the issue tracker but read the "getting help" section in the wiki first.

Installation

Install the latest release:

$ gem install carrierwave

In Rails, add it to your Gemfile:

gem 'carrierwave', '~> 1.0'

Finally, restart the server to apply the changes.

As of version 1.0, CarrierWave requires Rails 4.0 or higher and Ruby 2.0 or higher. If you're on Rails 3, you should use v0.11.0.

Getting Started

Start off by generating an uploader:

rails 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, including filesystem and cloud storage.

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

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 by creating a migration:

rails g migration add_avatar_to_users avatar:string
rails db:migrate

Open your model file and mount the uploader:

class User < ActiveRecord::Base
  mount_uploader :avatar, AvatarUploader
end

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] # Assign a file like this, or

# like this
File.open('somewhere') do |f|
  u.avatar = f
end

u.save!
u.avatar.url # => '/url/to/file.png'
u.avatar.current_path # => 'path/to/file.png'
u.avatar_identifier # => 'file.png'

Note: u.avatar will never return nil, even if there is no photo associated to it. To check if a photo was saved to the model, use u.avatar.file.nil? instead.

DataMapper, Mongoid, Sequel

Other ORM support has been extracted into separate gems:

There are more extensions listed in the wiki

Multiple file uploads

CarrierWave also has convenient support for multiple file upload fields.

ActiveRecord

Add a column which can store an array. This could be an array column or a JSON column for example. Your choice depends on what your database supports. For example, create a migration like this:

For databases with ActiveRecord json data type support (e.g. PostgreSQL, MySQL)

rails g migration add_avatars_to_users avatars:json
rails db:migrate

For database without ActiveRecord json data type support (e.g. SQLite)

rails g migration add_avatars_to_users avatars:string
rails db:migrate

Note: JSON datatype doesn't exists in SQLite adapter, that's why you can use a string datatype which will be serialized in model.

Open your model file and mount the uploader:

class User < ActiveRecord::Base
  mount_uploaders :avatars, AvatarUploader
  serialize :avatars, JSON # If you use SQLite, add this line.
end

Make sure that you mount the uploader with write (mount_uploaders) with s not (mount_uploader) in order to avoid errors when uploading multiple files

Make sure your file input fields are set up as multiple file fields. For example in Rails you'll want to do something like this:

<%= form.file_field :avatars, multiple: true %>

Also, make sure your upload controller permits the multiple file upload attribute, pointing to an empty array in a hash. For example:

params.require(:user).permit(:email, :first_name, :last_name, {avatars: []})

Now you can select multiple files in the upload dialog (e.g. SHIFT+SELECT), and they will automatically be stored when the record is saved.

u = User.new(params[:user])
u.save!
u.avatars[0].url # => '/url/to/file.png'
u.avatars[0].current_path # => 'path/to/file.png'
u.avatars[0].identifier # => '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.

If you store files outside the project root folder, you may want to define cache_dir in the same way:

class MyUploader < CarrierWave::Uploader::Base
  def cache_dir
    '/tmp/projectname-cache'
  end
end

Securing uploads

Certain files might be dangerous if uploaded to the wrong location, such as PHP files or other script files. CarrierWave allows you to specify a whitelist of allowed extensions or content types.

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_whitelist
    %w(jpg jpeg gif png)
  end
end

The same thing could be done using content types. Let's say we need an uploader that accepts only images. This can be done like this

class MyUploader < CarrierWave::Uploader::Base
  def content_type_whitelist
    /image\//
  end
end

You can use a blacklist to reject content types. Let's say we need an uploader that reject JSON files. This can be done like this

class NoJsonUploader < CarrierWave::Uploader::Base
  def content_type_blacklist
    ['application/text', 'application/json']
  end
end

Filenames and unicode chars

Another security issue you should care for is the file names (see Ruby On Rails Security Guide). By default, CarrierWave provides only English letters, arabic numerals and some symbols as white-listed characters in the file name. If you want to support local scripts (Cyrillic letters, letters with diacritics and so on), you have to override sanitize_regexp method. It should return regular expression which would match all non-allowed symbols.

CarrierWave::SanitizedFile.sanitize_regexp = /[^[:word:]\.\-\+]/

Also make sure that allowing non-latin characters won't cause a compatibility issue with a third-party plugins or client-side software.

Setting the content type

As of v0.11.0, the mime-types gem is a runtime dependency and the content type is set automatically. You no longer need to do this manually.

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*:

Note: You must have Imagemagick and MiniMagick installed to do image resizing. MiniMagick is a Ruby interface for Imagemagick which is a C program. This is why MiniMagick fails on 'bundle install' without Imagemagick installed.

Some documentation refers to RMagick instead of MiniMagick but MiniMagick is recommended.

To install Imagemagick on OSX with homebrew type the following:

$ brew install imagemagick
class MyUploader < CarrierWave::Uploader::Base
  include CarrierWave::MiniMagick

  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. The original aspect ratio will be kept. A version called thumb is then created, which is scaled to exactly 200 by 200 pixels.

If you would like to crop images to a specific height and width you can use the alternative option of '''resize_to_fill'''. It will make sure that the width and height specified are filled, only cropping if the aspect ratio requires it.

The uploader could be used like this:

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

uploader.url # => '/url/to/my_file.png'               # size: 800x800
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

Conditional versions

Occasionally you want to restrict the creation of versions on certain properties within the model or based on the picture itself.

class MyUploader < CarrierWave::Uploader::Base

  version :human, if: :is_human?
  version :monkey, if: :is_monkey?
  version :banner, if: :is_landscape?

private

  def is_human? picture
    model.can_program?(:ruby)
  end

  def is_monkey? picture
    model.favorite_food == 'banana'
  end

  def is_landscape? picture
    image = MiniMagick::Image.open(picture.path)
    image[:width] > image[:height]
  end

end

The model variable points to the instance object the uploader is attached to.

Create versions from existing versions

For performance reasons, it is often useful to create versions from existing ones instead of using the original file. If your uploader generates several versions where the next is smaller than the last, it will take less time to generate from a smaller, already processed image.

class MyUploader < CarrierWave::Uploader::Base

  version :thumb do
    process resize_to_fill: [280, 280]
  end

  version :small_thumb, from_version: :thumb do
    process resize_to_fill: [20, 20]
  end

end

The option :from_version uses the file cached in the :thumb version instead of the original version, potentially resulting in faster processing.

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 (don't forget to add it to the attr_accessible list as necessary). 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!, then save the object.

@user.remove_avatar!
@user.save
#=> true

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 attribute 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 %>

If you're using ActiveRecord, CarrierWave will indicate invalid URLs and download failures automatically with attribute validation errors. If you aren't, or you disable CarrierWave's validate_download option, you'll need to handle those errors yourself.

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(*args)
    "/images/fallback/" + [version_name, "default.png"].compact.join('_')
  end
end

Or if you are using the Rails asset pipeline:

class MyUploader < CarrierWave::Uploader::Base
  def default_url(*args)
    ActionController::Base.helpers.asset_path("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 re-upload and process the specified version or all versions, if none is passed as an argument.

When you are generating random unique filenames you have to call save! on the model after using recreate_versions!. This is necessary because recreate_versions! doesn't save the new filename to the database. Calling save! yourself will prevent that the database and file system are running out of sync.

instance = MyUploader.new
instance.recreate_versions!(:thumb, :large)

Or on a mounted uploader:

User.find_each do |user|
  user.avatar.recreate_versions!
end

Note: recreate_versions! will throw an exception on records without an image. To avoid this, scope the records to those with images or check if an image exists within the block. If you're using ActiveRecord, recreating versions for a user avatar might look like this:

User.find_each do |user|
  user.avatar.recreate_versions! if user.avatar?
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.directory_permissions = 0777
  config.storage = :file
end

Or alternatively:

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

If you're using Rails, create an initializer for this:

config/initializers/carrierwave.rb

If you want CarrierWave to fail noisily in development, you can change these configs in your environment file:

CarrierWave.configure do |config|
  config.ignore_integrity_errors = false
  config.ignore_processing_errors = false
  config.ignore_download_errors = false
end

Testing with CarrierWave

It's a good idea to test your 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? or Rails.env.cucumber?
  CarrierWave.configure do |config|
    config.storage = :file
    config.enable_processing = false
  end
end

Remember, if you have already set storage :something in your uploader, the storage setting from this initializer will be ignored.

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
  include CarrierWave::Test::Matchers

  let(:user) { double('user') }
  let(:uploader) { MyUploader.new(user, :avatar) }

  before do
    MyUploader.enable_processing = true
    File.open(path_to_file) { |f| uploader.store!(f) }
  end

  after do
    MyUploader.enable_processing = false
    uploader.remove!
  end

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

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

  it "makes the image readable only to the owner and not executable" do
    expect(uploader).to have_permissions(0600)
  end

  it "has the correct format" do
    expect(uploader).to be_format('png')
  end
end

If you're looking for minitest asserts, checkout carrierwave_asserts.

Setting the enable_processing flag on an uploader will prevent any of the versions from processing as well. Processing can be enabled for a single version by setting the processing flag on the version like so:

@uploader.thumb.enable_processing = true

Fog

If you want to use fog you must add in your CarrierWave initializer the following lines

config.fog_provider = 'fog' # 'fog/aws' etc. Defaults to 'fog'
config.fog_credentials = { ... } # Provider specific credentials

Using Amazon S3

Fog AWS is used to support Amazon S3. Ensure you have it in your Gemfile:

gem "fog-aws"

You'll need to provide your fog_credentials and a fog_directory (also known as a bucket) in an initializer. For the sake of performance it is assumed that the directory already exists, so please create it if it needs to be. You can also pass in additional options, as documented fully in lib/carrierwave/storage/fog.rb. Here's a full example:

CarrierWave.configure do |config|
  config.fog_provider = 'fog/aws'                        # required
  config.fog_credentials = {
    provider:              'AWS',                        # required
    aws_access_key_id:     'xxx',                        # required unless using use_iam_profile
    aws_secret_access_key: 'yyy',                        # required unless using use_iam_profile
    use_iam_profile:       true,                         # optional, defaults to false
    region:                'eu-west-1',                  # optional, defaults to 'us-east-1'
    host:                  's3.example.com',             # optional, defaults to nil
    endpoint:              'https://s3.example.com:8080' # optional, defaults to nil
  }
  config.fog_directory  = 'name_of_bucket'                                      # required
  config.fog_public     = false                                                 # optional, defaults to true
  config.fog_attributes = { cache_control: "public, max-age=#{365.days.to_i}" } # optional, defaults to {}
end

In your uploader, set the storage to :fog

class AvatarUploader < CarrierWave::Uploader::Base
  storage :fog
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

Fog is used to support Rackspace Cloud Files. Ensure you have it in your Gemfile:

gem "fog"

You'll need to configure a directory (also known as a container), username and API key in the initializer. For the sake of performance it is assumed that the directory already exists, so please create it if need be.

Using a US-based account:

CarrierWave.configure do |config|
  config.fog_provider = "fog/rackspace/storage"   # optional, defaults to "fog"
  config.fog_credentials = {
    provider:           'Rackspace',
    rackspace_username: 'xxxxxx',
    rackspace_api_key:  'yyyyyy