= CarrierWave

http://carrierwave.rubyforge.org

== Summary

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

== Description

* RDoc Documentation {available at Rubyforge}[http://carrierwave.rubyforge.org/rdoc].
* Source code {hosted at GitHub}[http://github.com/jnicklas/carrierwave]
* Please {report any issues}[http://github.com/jnicklas/carrierwave/issues] on GitHub
* Please direct any questions at the {mailing list}[http://groups.google.com/group/carrierwave]
* Check out the {example app}[http://github.com/jnicklas/carrierwave-example-app]

== 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 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, MongoMapper

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.

== 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 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 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 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 <code>remove_avatar!</code>.

== 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 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

== 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

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 <code>CarrierWave::Uploader#url</code> method to return
the url to the file on Amazon S3.

Alternatively, and especially if your bucket is located in Europe, you can use the
RightAWS library by setting the storage to :right_s3

    class AvatarUploader < CarrierWave::Uploader::Base
      storage :right_s3
    end

CarrierWave uses the RightAWS S3 Interface directly, meaning that the performance issues
mentioned by Jonathan Yurek for paperclip do not apply: http://groups.google.com/group/paperclip-plugin/browse_thread/thread/d4dc166a9a5f0df4#


== 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 <code>:grid_fs</code>:

    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
<code>CarrierWave::RMagick#resize_to_fill</code> 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:

http://github.com/probablycorey/mini_magick

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

http://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 <code>Paperclip::Compatibility::Paperclip</code> 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

== License

Copyright (c) 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!