How to resize images before uploading with Active Storage (linked with AWS)

Question

I try to use Active Storage with Amazon Web Services, instead of Carrierwave and Cloudinary.

With Carrierwave I had some features that allow to resize images before uploading trough an UploaderController.

But how to do that with Active Storage ?

I try this :

Gemfile :

gem 'aws-sdk-s3', require: false
gem 'image_processing', '~> 1.2'
gem 'mini_magick', '~>4.9'

item.rb

class Item < ApplicationRecord
    has_one_attached :photo
end

I have a form in my view :

<%= f.input :photo, input_html: { accept: ('image') } %>

I get this object as photo :

#<ActiveStorage::Attached::One:0x00005641d296e1b8 @name="photo", @record=#<Item id: nil, name: "test0941", verbe: "To Lend", collection_id: nil, created_at: nil, updated_at: nil, price_cents: 0, description: "", category_id: 78, photo: nil>, @dependent=:purge_later>

And in my controller :

@item = Item.new(item_params)
@item.photo.combine_options do |b|
    b.resize "250x200>"
end

I can't achieve to resize my photo with methods of MiniMagick gem.

Does anybody have any ideas to do that ?

Thanks for your help, Thibault

Answer 1

If params[:item][:photo] is the param from your post you can add

image = MiniMagick::Image.new(params[:item][:photo].tempfile.path)
image.resize "250x200>"

With ImageProcessing::Vips (default in rails7)

path = params[:game][:photo].tempfile.path
image = ImageProcessing::Vips.source(path)
result = image.resize_to_limit!(800, 800)
params[:game][:photo].tempfile = result

Answer 2

I did it like this:

# config/initializers/activestorage.rb

# Ability to auto apply :default variant (if defined) before uploading original image
Rails.application.config.after_initialize do
  ActiveStorage::Blob.class_eval do
    alias_method :upload_without_unfurling_orig, :upload_without_unfurling
    
    def upload_without_unfurling(io)
      variant = attachments.first.send(:variants)
      default_variant = variant[:default]
      if default_variant
        ActiveStorage::Variation.wrap(default_variant).transform(io) do |output|
          unfurl output, identify: identify
          upload_without_unfurling_orig(output)
        end
      else
        upload_without_unfurling_orig(io)
      end
    end
  end
end

# user.rb
class User < ApplicationRecord
  has_one_attached :photo do |attachable|
    attachable.variant :thumb, resize_to_fill: [100, nil]
    # This variant will be applied before uploading the original image
    attachable.variant :default, strip: true, quality: 70, resize_to_fill: [500, 500]
  end
end

# rspec
RSpec.describe User, type: :model do
  describe 'when uploading photo' do
    it 'applies :default variant before uploading the original image' do
      allow(ActiveStorage::Variation).to receive(:wrap).and_call_original
      create(:user, :with_photo)
      exp_args = hash_including(resize_to_fill: [500, 500])
      expect(ActiveStorage::Variation).to have_received(:wrap).with(exp_args)
    end
  end
end