Active Storage makes it simple to upload and reference files in cloud services like Amazon S3, Google Cloud Storage, or Microsoft Azure Storage, and attach those files to Active Records. Supports having one main service and mirrors in other services for redundancy. It also provides a disk service for testing or local deployments, but the focus is on cloud storage.
Files can be uploaded from the server to the cloud or directly from the client to the cloud.
You can read more about Active Storage in the Active Storage Overview guide.
Compared to other storage solutions
A key difference to how Active Storage works compared to other attachment solutions in Rails is through the use of built-in Blob and Attachment models (backed by Active Record). This means existing application models do not need to be modified with additional columns to associate with files. Active Storage uses polymorphic associations via the
Attachment join model, which then connects to the actual
Blob models store attachment metadata (filename, content-type, etc.), and their identifier key in the storage service. Blob models do not store the actual binary data. They are intended to be immutable in spirit. One file, one blob. You can associate the same blob with multiple application models as well. And if you want to do transformations of a given
Blob, the idea is that you'll simply create a new one, rather than attempt to mutate the existing one (though of course you can delete the previous version later if you don't need it).
bin/rails active_storage:install to copy over active_storage migrations.
NOTE: If the task cannot be found, verify that
require "active_storage/engine" is present in
class User < ApplicationRecord # Associates an attachment and a blob. When the user is destroyed they are # purged by default (models destroyed, and resource files deleted). has_one_attached :avatar end # Attach an avatar to the user. user.avatar.attach(io: File.open("/path/to/face.jpg"), filename: "face.jpg", content_type: "image/jpg") # Does the user have an avatar? user.avatar.attached? # => true # Synchronously destroy the avatar and actual resource files. user.avatar.purge # Destroy the associated models and actual resource files async, via Active Job. user.avatar.purge_later # Does the user have an avatar? user.avatar.attached? # => false # Generate a permanent URL for the blob that points to the application. # Upon access, a redirect to the actual service endpoint is returned. # This indirection decouples the public URL from the actual one, and # allows for example mirroring attachments in different services for # high-availability. The redirection has an HTTP expiration of 5 min. url_for(user.avatar) class AvatarsController < ApplicationController def update # params[:avatar] contains an ActionDispatch::Http::UploadedFile object Current.user.avatar.attach(params.require(:avatar)) redirect_to Current.user end end
class Message < ApplicationRecord has_many_attached :images end
<%= form_with model: @message, local: true do |form| %> <%= form.text_field :title, placeholder: "Title" %><br> <%= form.text_area :content %><br><br> <%= form.file_field :images, multiple: true %><br> <%= form.submit %> <% end %>
class MessagesController < ApplicationController def index # Use the built-in with_attached_images scope to avoid N+1 @messages = Message.all.with_attached_images end def create = Message.create! params.require(:message).permit(:title, :content) .images.attach(params[:message][:images]) redirect_to end def show @message = Message.find(params[:id]) end end
Variation of image attachment:
<%# Hitting the variant URL will lazy transform the original blob and then redirect to its new service location %> <%= image_tag user.avatar.variant(resize_to_limit: [100, 100]) %>
File serving strategies
Active Storage supports two ways to serve files: redirecting and proxying.
Active Storage generates stable application URLs for files which, when accessed, redirect to signed, short-lived service URLs. This relieves application servers of the burden of serving file data. It is the default file serving strategy.
When the application is configured to proxy files by default, use the
_url route helpers to redirect instead:
<%= image_tag rails_storage_redirect_path(@user.avatar) %>
Optionally, files can be proxied instead. This means that your application servers will download file data from the storage service in response to requests. This can be useful for serving files from a CDN.
Explicitly proxy attachments using the
_url route helpers:
<%= image_tag rails_storage_proxy_path(@user.avatar) %>
Or configure Active Storage to use proxying by default:
# config/initializers/active_storage.rb Rails.application.config.active_storage.resolve_model_to_route = :rails_storage_proxy
Direct upload installation
Using the asset pipeline:
//= require activestorage
Using the npm package:
import * as ActiveStorage from "@rails/activestorage" ActiveStorage.start()
Annotate file inputs with the direct upload URL.
<%= form.file_field :attachments, multiple: true, direct_upload: true %>
That's it! Uploads begin upon form submission.
|Event name||Event target||Event data (
||None||A form containing files for direct upload fields was submitted.|
||Dispatched for every file after form submission.|
||A direct upload is starting.|
||Before making a request to your application for direct upload metadata.|
||Before making a request to store a file.|
||As requests to store files progress.|
||An error occurred. An
||A direct upload has ended.|
||None||All direct uploads have ended.|
Active Storage is released under the MIT License.
API documentation is at:
Bug reports for the Ruby on Rails project can be filed here:
Feature requests should be discussed on the rails-core mailing list here: