How to install ActiveStorage in a rails application.

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Installation

Add or uncomment the following line in your Gemfile:

gem "image_processing", ">= 1.2"

Now based on the cloud storage service you want to use, add the respective gem:

gem "aws-sdk-s3", require: false # For Amazon S3
gem "azure-storage-blob", "~> 2.0", require: false # For Microsoft Azure Storage Service
gem "google-cloud-storage", "~> 1.11", require: false # For Google Cloud Storage

Run the following command to install ActiveStorage.

bin/rails active_storage:install
bin/rails db:migrate

This command will create the necessary migrations to store the attachments.

If you use UUIDs for primary key you will need to ensure that the primary key is set to :uuid in the migration file. You can do this by adding the following line to the config file: Rails.application.config.generators { |g| g.orm :active_record, primary_key_type: :uuid }

Add Active Storage services in config/storage.yml:

local:
  service: Disk
  root: <%= Rails.root.join("storage") %>

test:
  service: Disk
  root: <%= Rails.root.join("tmp/storage") %>

amazon:
  service: S3
  access_key_id: <%= Rails.application.credentials.dig(:aws, :access_key_id) %>
  secret_access_key: <%= Rails.application.credentials.dig(:aws, :secret_access_key) %>
  bucket: <%= Rails.application.credentials.dig(:aws, :bucket) %>
  region: us-east-1

Configure the services in environment specific files

Development Environment:

# config/environments/development.rb
config.active_storage.service = :local

Test Environment:

# config/environments/test.rb
config.active_storage.service = :test

Production Environment:

# config/environments/production.rb
config.active_storage.service = :amazon

Usage

has_one_attached

Rails provides a generator to create a model with an attachment:

bin/rails generate model User avatar:attachment

The above command will add the following content in app/models/user.rb:

class User < ApplicationRecord
  has_one_attached :avatar
end

has_many_attached

Rails provides a generator to create a model with an attachment:

bin/rails generate model Post images:attachments

The above command will add the following content in app/models/post.rb:

class Post < ApplicationRecord
  has_many_attached :images
end

Attaching a file / image to the model

Make use of attach to attach a file/image to the model.

# Attaching a file/image
user.avatar.attach(
  io: File.open("/path/to/file.jpg"),
  filename: "file.jpg",
  content_type: "image/jpg"
)
post.images.attach(
  io: File.open("/path/to/file.jpg"),
  filename: "file.jpg",
  content_type: "image/jpg"
)

In order to check if the attachment is present, you can use the following method:

user.avatar.attached?
post.images.attached?

Removing the attachments

# Remove the attachment
user.avatar.purge

# Use ActiveJob to remove the attachment in the background
user.avatar.purge_later

References

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