**DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON http://guides.rubyonrails.org.** Active Storage Overview ======================= This guide covers how to attach files to your Active Record models. After reading this guide, you will know: * How to attach one or many files to a record. * How to delete an attached file. * How to link to an attached file. * How to use variants to transform images. * How to generate an image representation of a non-image file, such as a PDF or a video. * How to send file uploads directly from browsers to a storage service, bypassing your application servers. * How to clean up files stored during testing. * How to implement support for additional storage services. -------------------------------------------------------------------------------- What is Active Storage? ----------------------- Active Storage facilitates uploading files to a cloud storage service like Amazon S3, Google Cloud Storage, or Microsoft Azure Storage and attaching those files to Active Record objects. It comes with a local disk-based service for development and testing and supports mirroring files to subordinate services for backups and migrations. Using Active Storage, an application can transform image uploads with [ImageMagick](https://www.imagemagick.org), generate image representations of non-image uploads like PDFs and videos, and extract metadata from arbitrary files. ## Setup Active Storage uses two tables in your application’s database named `active_storage_blobs` and `active_storage_attachments`. After upgrading your application to Rails 5.2, run `rails active_storage:install` to generate a migration that creates these tables. Use `rails db:migrate` to run the migration. You need not run `rails active_storage:install` in a new Rails 5.2 application: the migration is generated automatically. Declare Active Storage services in `config/storage.yml`. For each service your application uses, provide a name and the requisite configuration. The example below declares three services named `local`, `test`, and `amazon`: ```yaml local: service: Disk root: <%= Rails.root.join("storage") %> test: service: Disk root: <%= Rails.root.join("tmp/storage") %> amazon: service: S3 access_key_id: "" secret_access_key: "" ``` Tell Active Storage which service to use by setting `Rails.application.config.active_storage.service`. Because each environment will likely use a different service, it is recommended to do this on a per-environment basis. To use the disk service from the previous example in the development environment, you would add the following to `config/environments/development.rb`: ```ruby # Store files locally. config.active_storage.service = :local ``` To use the Amazon S3 service in production, you add the following to `config/environments/production.rb`: ```ruby # Store files on Amazon S3. config.active_storage.service = :amazon ``` Continue reading for more information on the built-in service adapters (e.g. `Disk` and `S3`) and the configuration they require. ### Disk Service Declare a Disk service in `config/storage.yml`: ```yaml local: service: Disk root: <%= Rails.root.join("storage") %> ``` ### Amazon S3 Service Declare an S3 service in `config/storage.yml`: ```yaml amazon: service: S3 access_key_id: "" secret_access_key: "" region: "" bucket: "" ``` Add the [`aws-sdk-s3`](https://github.com/aws/aws-sdk-ruby) gem to your `Gemfile`: ```ruby gem "aws-sdk-s3", require: false ``` ### Microsoft Azure Storage Service Declare an Azure Storage service in `config/storage.yml`: ```yaml azure: service: AzureStorage path: "" storage_account_name: "" storage_access_key: "" container: "" ``` Add the [`azure-storage`](https://github.com/Azure/azure-storage-ruby) gem to your `Gemfile`: ```ruby gem "azure-storage", require: false ``` ### Google Cloud Storage Service Declare a Google Cloud Storage service in `config/storage.yml`: ```yaml google: service: GCS credentials: <%= Rails.root.join("path/to/keyfile.json") %> project: "" bucket: "" ``` Optionally provide a Hash of credentials instead of a keyfile path: ```yaml google: service: GCS credentials: type: "service_account" project_id: "" private_key_id: <%= Rails.application.credentials.dig(:gcs, :private_key_id) %> private_key: <%= Rails.application.credentials.dig(:gcs, :private_key) %> client_email: "" client_id: "" auth_uri: "https://accounts.google.com/o/oauth2/auth" token_uri: "https://accounts.google.com/o/oauth2/token" auth_provider_x509_cert_url: "https://www.googleapis.com/oauth2/v1/certs" client_x509_cert_url: "" project: "" bucket: "" ``` Add the [`google-cloud-storage`](https://github.com/GoogleCloudPlatform/google-cloud-ruby/tree/master/google-cloud-storage) gem to your `Gemfile`: ```ruby gem "google-cloud-storage", "~> 1.3", require: false ``` ### Mirror Service You can keep multiple services in sync by defining a mirror service. When a file is uploaded or deleted, it's done across all the mirrored services. Mirrored services can be used to facilitate a migration between services in production. You can start mirroring to the new service, copy existing files from the old service to the new, then go all-in on the new service. Define each of the services you'd like to use as described above and reference them from a mirrored service. ```yaml s3_west_coast: service: S3 access_key_id: "" secret_access_key: "" region: "" bucket: "" s3_east_coast: service: S3 access_key_id: "" secret_access_key: "" region: "" bucket: "" production: service: Mirror primary: s3_east_coast mirrors: - s3_west_coast ``` NOTE: Files are served from the primary service. Attaching Files to Records -------------------------- ### `has_one_attached` The `has_one_attached` macro sets up a one-to-one mapping between records and files. Each record can have one file attached to it. For example, suppose your application has a `User` model. If you want each user to have an avatar, define the `User` model like this: ```ruby class User < ApplicationRecord has_one_attached :avatar end ``` You can create a user with an avatar: ```ruby class SignupController < ApplicationController def create user = User.create!(user_params) session[:user_id] = user.id redirect_to root_path end private def user_params params.require(:user).permit(:email_address, :password, :avatar) end end ``` Call `avatar.attach` to attach an avatar to an existing user: ```ruby Current.user.avatar.attach(params[:avatar]) ``` Call `avatar.attached?` to determine whether a particular user has an avatar: ```ruby Current.user.avatar.attached? ``` ### `has_many_attached` The `has_many_attached` macro sets up a one-to-many relationship between records and files. Each record can have many files attached to it. For example, suppose your application has a `Message` model. If you want each message to have many images, define the `Message` model like this: ```ruby class Message < ApplicationRecord has_many_attached :images end ``` You can create a message with images: ```ruby class MessagesController < ApplicationController def create message = Message.create!(message_params) redirect_to message end private def message_params params.require(:message).permit(:title, :content, images: []) end end ``` Call `images.attach` to add new images to an existing message: ```ruby @message.images.attach(params[:images]) ``` Call `images.attached?` to determine whether a particular message has any images: ```ruby @message.images.attached? ``` Removing Files -------------- To remove an attachment from a model, call `purge` on the attachment. Removal can be done in the background if your application is setup to use Active Job. Purging deletes the blob and the file from the storage service. ```ruby # 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 ``` Linking to Files ---------------- 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. ```ruby url_for(user.avatar) ``` To create a download link, use the `rails_blob_{path|url}` helper. Using this helper allows you to set the disposition. ```ruby rails_blob_path(user.avatar, disposition: "attachment") ``` Transforming Images ------------------- To create variation of the image, call `variant` on the Blob. You can pass any [MiniMagick](https://github.com/minimagick/minimagick) supported transformation to the method. To enable variants, add `mini_magick` to your `Gemfile`: ```ruby gem 'mini_magick' ``` When the browser hits the variant URL, Active Storage will lazy transform the original blob into the format you specified and redirect to its new service location. ```erb <%= image_tag user.avatar.variant(resize: "100x100") %> ``` Previewing Files ---------------- Some non-image files can be previewed: that is, they can be presented as images. For example, a video file can be previewed by extracting its first frame. Out of the box, Active Storage supports previewing videos and PDF documents. ```erb ``` WARNING: Extracting previews requires third-party applications, `ffmpeg` for video and `mutool` for PDFs. These libraries are not provided by Rails. You must install them yourself to use the built-in previewers. Before you install and use third-party software, make sure you understand the licensing implications of doing so. Direct Uploads -------------- Active Storage, with its included JavaScript library, supports uploading directly from the client to the cloud. ### Direct upload installation 1. Include `activestorage.js` in your application's JavaScript bundle. Using the asset pipeline: ```js //= require activestorage ``` Using the npm package: ```js import * as ActiveStorage from "activestorage" ActiveStorage.start() ``` 2. Annotate file inputs with the direct upload URL. ```ruby <%= form.file_field :attachments, multiple: true, direct_upload: true %> ``` 3. That's it! Uploads begin upon form submission. ### Direct upload JavaScript events | Event name | Event target | Event data (`event.detail`) | Description | | --- | --- | --- | --- | | `direct-uploads:start` | `
` | None | A form containing files for direct upload fields was submitted. | | `direct-upload:initialize` | `` | `{id, file}` | Dispatched for every file after form submission. | | `direct-upload:start` | `` | `{id, file}` | A direct upload is starting. | | `direct-upload:before-blob-request` | `` | `{id, file, xhr}` | Before making a request to your application for direct upload metadata. | | `direct-upload:before-storage-request` | `` | `{id, file, xhr}` | Before making a request to store a file. | | `direct-upload:progress` | `` | `{id, file, progress}` | As requests to store files progress. | | `direct-upload:error` | `` | `{id, file, error}` | An error occurred. An `alert` will display unless this event is canceled. | | `direct-upload:end` | `` | `{id, file}` | A direct upload has ended. | | `direct-uploads:end` | `` | None | All direct uploads have ended. | ### Example You can use these events to show the progress of an upload. ![direct-uploads](https://user-images.githubusercontent.com/5355/28694528-16e69d0c-72f8-11e7-91a7-c0b8cfc90391.gif) To show the uploaded files in a form: ```js // direct_uploads.js addEventListener("direct-upload:initialize", event => { const { target, detail } = event const { id, file } = detail target.insertAdjacentHTML("beforebegin", `
${file.name}
`) }) addEventListener("direct-upload:start", event => { const { id } = event.detail const element = document.getElementById(`direct-upload-${id}`) element.classList.remove("direct-upload--pending") }) addEventListener("direct-upload:progress", event => { const { id, progress } = event.detail const progressElement = document.getElementById(`direct-upload-progress-${id}`) progressElement.style.width = `${progress}%` }) addEventListener("direct-upload:error", event => { event.preventDefault() const { id, error } = event.detail const element = document.getElementById(`direct-upload-${id}`) element.classList.add("direct-upload--error") element.setAttribute("title", error) }) addEventListener("direct-upload:end", event => { const { id } = event.detail const element = document.getElementById(`direct-upload-${id}`) element.classList.add("direct-upload--complete") }) ``` Add styles: ```css /* direct_uploads.css */ .direct-upload { display: inline-block; position: relative; padding: 2px 4px; margin: 0 3px 3px 0; border: 1px solid rgba(0, 0, 0, 0.3); border-radius: 3px; font-size: 11px; line-height: 13px; } .direct-upload--pending { opacity: 0.6; } .direct-upload__progress { position: absolute; top: 0; left: 0; bottom: 0; opacity: 0.2; background: #0076ff; transition: width 120ms ease-out, opacity 60ms 60ms ease-in; transform: translate3d(0, 0, 0); } .direct-upload--complete .direct-upload__progress { opacity: 0.4; } .direct-upload--error { border-color: red; } input[type=file][data-direct-upload-url][disabled] { display: none; } ``` Discarding Files Stored During System Tests ------------------------------------------- System tests clean up test data by rolling back a transaction. Because destroy is never called on an object, the attached files are never cleaned up. If you want to clear the files, you can do it in an `after_teardown` callback. Doing it here ensures that all connections created during the test are complete and you won't receive an error from Active Storage saying it can't find a file. ```ruby class ApplicationSystemTestCase < ActionDispatch::SystemTestCase driven_by :selenium, using: :chrome, screen_size: [1400, 1400] def remove_uploaded_files FileUtils.rm_rf("#{Rails.root}/storage_test") end def after_teardown super remove_uploaded_files end end ``` If your system tests verify the deletion of a model with attachments and you're using Active Job, set your test environment to use the inline queue adapter so the purge job is executed immediately rather at an unknown time in the future. You may also want to use a separate service definition for the test environment so your tests don't delete the files you create during development. ```ruby # Use inline job processing to make things happen immediately config.active_job.queue_adapter = :inline # Separate file storage in the test environment config.active_storage.service = :local_test ``` Implementing Support for Other Cloud Services --------------------------------------------- If you need to support a cloud service other than these, you will need to implement the Service. Each service extends [`ActiveStorage::Service`](https://github.com/rails/rails/blob/master/activestorage/lib/active_storage/service.rb) by implementing the methods necessary to upload and download files to the cloud.