Introduction When storing static files in Rails, the first toolsets I reach for are 3rd party gems like: CarrierWave or Paperclip (before they in favour of Active Storage). Active Storage was introduced with Rails 5.2. deprecated it 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 , generate image representations of non-image uploads like PDFs and videos, and extract metadata from arbitrary files. ImageMagick In this article, we will focus on how to make the 's files by creating a simple app. validation of active storage Go in the terminal and generate a new app rails new app After cd in the app folder crated, let's generate a simple blog app with the scaffold command. rails g scaffold Post string text title: content: When the process finished don't forget to migrate rails migrate db: We can lunch the server now rails server And by visiting the in our browser, we can see the application running. localhost:3000/posts/index Let's set the routes to posts/index by editing the file config/routes.rb Rails. .routes.draw do resources :posts root : 'posts #config/routes.rb application to #index' end Let's now add the image to our Post with active storage. Set up First, we need to install active storage in our project. We will need to run this command on the terminal lines rails install active_storage: After running this command, Rails generates a migration for you. Upon inspection of that migration, and creates 2 different tables: is up first, it contains information about files like metadata, filename, checksum, and so on. active_storage_blobs The next table, , stores the name of any file attachment as well as the record, which is also a polymorphic association. Why is that important? It allows you to use file attachments on model without cluttering your model's migrations with table columns specifically for file data. active_storage_attachments any Don't forget to run the migration command At the end rails migrate db: Adding the image to the Model, View and Controller By visiting our We will attach the image to our post app/models/post.rb has_one_attached #app/models/post.rb < ApplicationRecord class Post :image end We will again need to add the image in our controller just at the end in the post_params method add the image to the properties of the model. params. ( ).permit( , , ) #app/controller/posts_controller.rb def post_params require :post :title :content :image end We will now go in our views and add the image. In the we will be editing the file by adding a new class after the content. app/views/posts/_form.html.erb <%= %> <%= %> #app/views/posts/_form.html.erb < = > div class "field" form.label :image form.file_field :image </ > div Now we need to load the image in the index and show <% %> <%= %> <% %> #app/views/posts/index.html.erb post.image.attached? if < > td image_tag post.image </ > td end <% %> <%= %> <% %> #app/views/posts/show.html.erb < > p @post.image.attached? if image_tag @post.image end </ > p And voila, we can add the image to the post. But what if we want to have the image associate to each post? In this case, we will need to validate our image so that the user can not create a post without an image. Let's first validate our title and content fields has_one_attached validates , , validates , { , } validates , { , } # app/models/post.rb < ApplicationRecord class Post :image :title :content presence: true :title length: minimum: 5 maximum: 25 :content length: minimum: 10 maximum: 50 end By editing our file, we prevent the user to submit an empty title and empty content field. He can't also submit the title with content less than 5 or more than 25 characters, as well as the content, can't have more than 50 or less than 10 characters. post.rb Validation with Active Storage We've now validated our title and content, but we need again to prevent the user to create a post without an image associated with it. It is very simple, we can do it by adding this one line. But before that, we need first to add the in the Gemfile and run after. gem 'active_storage_validations' bundle install # app/models/post.rb validates :image, attached: true , content_type: %i[png jpg jpeg] We prevent the user to add files of types different from png, jpg and jpeg and we say that the image must be attached to the post. So he can't submit a post without an associated image. Restart the server to see the changes. Voila, we reach our goal, now the user can not submit a Post with an empty image.
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