Upload Files To Rails App Using Active Storage

by: Lisette del Pino

Intro: Local Storage for Development:

Note: This is a tutorial for Ruby Active Storage file upload for development and testing purposes. Once your Rails app goes into production, use Amazon, Google, or Azure services

Note: I encourage you to read/explore as much as you can with each command. In this tutorial, I include the output location corresponding to the command you just wrote so that you can see what the commands are doing to your Rails app. Get familiar with the structure of your app, and all future Rails endeavors will feel 100x easier!

Step 1 :

Make sure that in config/storage.yml you have (setting storage configuration to local Disk):

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

Step 2:

Make sure that in config\environments\development.rb you have the development configuration set to store files locally!

  # Store uploaded files on the local file system (see config/storage.yml for options)
  config.active_storage.service = :local

Step 3:

To set up the database for active storage, in your terminal for the project, write rails active_storage:install - This creates a migration file that you can look at under : db\migrate, look for the migration with a similar command name. Take a peek! - Notice we are storing some file meta-data, and NOT the file information itself. Why?

Step 4:

If you haven’t set up your relationship already, head to app\models and edit your ruby file corresponding to the model you are setting up file upload for. So, if users are getting a single profile picture, go into user.rb and:

has_one_attached :profile_img

Step 5 :

Head into your controller to define behavior now, in app\controllers\users_controller.rb , or whichever controller corresponds to the model file you just edited. Under private, under user_params def, .permit a profile_img. So, it should look something like (but it should have other permitted fields, according to your app):

 # Only allow a list of trusted parameters through.
    def user_params
      params.require(:leaf).permit(:cover_img)
    end

Step 6:

Modify your creation forms to support uploading by

Amazon S3, Azure, Google Cloud:

These services are better used in production. Why? In production, if several VMs are running the same Rails App, you keep creating the same files over and over in local storage. This upload style takes up unnecessary space and doesn’t allow for horizontal growth. By uploading files to another service, you can access the same file in one place across several VMs.