Carrierwave::ActiveRecord

CarrierWave::ActiveRecord is a CarrierWave plugin which stores file data using ActiveRecord. It relies on ActiveRecord for database independence. At this time, it is tested against only MySQL.

Installation

Add the gem

Add it to your Gemfile:

gem 'carrierwave-activerecord'

And install:

$ bundle

Or manually:

$ gem install carrierwave-activerecord

Usage

To use the ActiveRecord store, add the following to your uploader:

storage :active_record

Storing files

By default, the gem uses a table named carrier_wave_files with the following columns:

• id: integer
• medium_hash: string
• binary: binary

The table name is a CarrierWave configurable, e.g.:

configure do |config|
  config.active_record_tablename = 'my_file_storage_table'
end

Rails

If you do not have a suitable table, you may generate a migration to create the default table:

$ rails generate carrierwave_activerecord # => db/migrate/..._create_carrierwave_files.rb
$ rake db:migrate

Outside Rails

If you are already using ActiveRecord as your ORM, the storage provider will use the existing connection. Thus, it will work in Rails without any additional configuration.

If you are not using ActiveRecord as your ORM, you will need to setup the connection to the database.

Serving files

Rails

When used with Rails, the gem attempts to follow routing conventions.

File URLs point to the resource on which the uploader is mounted, using the mounted attribute name as the tail portion of the URL.

To serve the files while preserving security, add to your application's routes and appropriate controllers.

For example:

Given a people resource with an uploader mounted on the avatar field:

# app/models/person.rb
class Person < ActiveRecord::Base
  attr_accessible :avatar
  mount_uploader :avatar, AvatarUploader
end

Each avatar file will be available underneath it's corresponding person:

/person/1/avatar

Adding a member GET route to the resource will generate a named route for use in controllers and views:

# config/routes.rb
MyApp::Application.routes.draw do
  resources :people do
    # At the present time, resourcing files has not been tested.
    member { get 'avatar' }
end

Then implement the method PeopleController#avatar to serve the avatar:

# app/controllers/people_controller.rb
class PeopleController

  # before_filters for auth, etc.
  # ...

  def avatar
    person = Person.find(params[:id])
    send_data(person.avatar.read, filename: person.avatar.file.filename)
  end
end

Outside Rails: default routes

Without Rails, file URLs are generated from two parts.

• the downloader_path_prefix, common to all files
• the identifier, a SHA1 particular to each file

The path prefix is configurable in your CarrierWave configure block, as downloader_path_prefix, the default is /files.

For example:

GET /files/afdd0c3f8578270aae2bd1784b46cefa0bec8fa6 HTTP/1.1

Outside Rails: custom routes

Finally, you have the option of overriding the URL in each uploader:

# app/uploaders/avatar_uploader.rb
class AvatarUploader < CarrierWave::Uploader::Base
  def url
    "/a/custom/url/to/avatar/#{uploader.model.id}"
  end
end

Further reading

An example project

The following example and test project tracks the gem: https://github.com/richardkmichael/carrierwave-activerecord-project

How to add a storage provider

A work-in-progress guide to writing a CarrierWave storage provider is here: https://github.com/richardkmichael/carrierwave-activerecord/wiki/Howto:-Adding-a-new-storage-engine

[3] pry(#<CarrierWave::Mount::Mounter>)> self
=> #<CarrierWave::Mount::Mounter:0x00000102b67aa8
 @column=:file,
 @integrity_error=nil,
 @options={},
 @processing_error=nil,
 @record=
  #<ArticleFile id: 5, file: "my_uploaded_file.txt", article_id: 4, created_at: "2012-06-02 11:42:10", updated_at: "2012-06-02 11:42:10">,
 @uploader=,
 @uploader_options={:mount_on=>nil}>

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request