Migrating from one file attachment library to another can be a challenging task, but with Rails’ built-in Active Storage, the process becomes much smoother.
Step 1: Preparing the Application
Install the Active Storage gem by adding it to your Gemfile:
1
gem 'activestorage'
Run the bundle install command:
1
bundle install
Run the active_storage:install command to generate the necessary migrations:
1
rails active_storage:install
Configure Active Storage by setting up the desired storage service (local or cloud-based) in config/storage.yml.
Configure the desired storage service in config/environments/development.rb and config/environments/production.rb:
1
config.active_storage.service = :local # or :amazon, :google, etc.
Step 2: Adapting the Model
Update the model that uses Paperclip to switch to Active Storage. For example, if you have a model named Attachment with a Paperclip attachment named file, you would make the following changes:
1
2
3
4
5
6
7
class Attachment < ApplicationRecord
# Remove Paperclip attachment declaration
# has_attached_file :file, ...
# Add Active Storage attachment declaration
has_one_attached :file
end
Update the model associations and validations related to the attachment. For example, if you have a User model that has many attachments with Paperclip, you would modify it as follows:
1
2
3
4
5
6
7
class User < ApplicationRecord
# Remove the Paperclip association
# has_many :attachments, as: :attachable
# Add the Active Storage association
has_many_attached :attachments
end
Step 3: Updating the Views and Controllers
Replace any Paperclip-specific view code with Active Storage equivalents. For example, if you were displaying an image using Paperclip, you would modify the view code as follows:
1
2
3
4
5
<!-- Before -->
<%= image_tag @attachment.file.url %>
<!-- After -->
<%= image_tag url_for(@attachment.file) %>
Adjust the view code to render the appropriate URLs for Active Storage attachments. For example, if you had a download link for a Paperclip attachment, you would update it as follows:
1
2
3
4
5
<!-- Before -->
<%= link_to 'Download', @attachment.file.url %>
<!-- After -->
<%= link_to 'Download', url_for(@attachment.file) %>
Modify the controller actions to handle file uploads using Active Storage. For example, if you had a create action in your controller that handled file uploads with Paperclip, you would update it as follows:
1
2
3
4
5
6
7
8
9
def create
@attachment = Attachment.new(attachment_params)
@attachment.file.attach(params[:attachment][:file]) # Attach the file using Active Storage
if @attachment.save
# ...
else
# ...
end
end
Step 4: Data Migration
Create a new data migration to transfer existing Paperclip attachments to Active Storage. For example:
1
$ rails generate migration MigratePaperclipAttachmentsToActiveStorage
In the generated migration file, write the migration code to transfer the attachments. Here’s an example:
1
2
3
4
5
6
7
8
9
10
11
12
13
class MigratePaperclipAttachmentsToActiveStorage < ActiveRecord::Migration[6.1]
def up
Attachment.find_each do |attachment|
attachment.file.attach(io: File.open(attachment.file.path), filename: attachment.file_file_name)
end
end
def
down
# If needed, implement a rollback method
end
end
Step 5: Testing and Cleanup
Update existing tests or add new tests to ensure proper functionality after the migration.
Remove any Paperclip-related code, migrations, or configuration files from the project.