This plugin for Merb and Rails provides a simple and extremely flexible way to upload files.
RDoc Documentation available at Rubyforge.
Source code hosted at GitHub
Please report any issues on GitHub
Please direct any questions at the mailing list
Install the latest stable release:
[sudo] gem install carrierwave
CarrierWave is hosted only on Gemcutter as of version 0.4.0.
In Merb, add it as a dependency to your config/dependencies.rb:
In Rails, add it to your environment.rb:
Start off by generating an uploader:
merb-gen uploader Avatar
or in Rails:
script/generate uploader Avatar
this should give you a file in:
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.:
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.
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
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 => [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 %>
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
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
class AvatarUploader < CarrierWave::Uploader::Base permissions 0777 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 +CarrierWave::Uploader#url+ method to return the url to the file on Amazon S3
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
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.
ImageScience works the same way as RMagick.
class AvatarUploader < CarrierWave::Uploader::Base include CarrierWave::ImageScience process :resize_to_fill => [200, 200] end
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:
And the ImageMagick command line options for more for whats on offer:
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
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.
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.'
These people have contributed their time and effort to CarrierWave:
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.
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!