How to attach images in mailer from active storage association in Rails - ruby-on-rails-5

Question

In rails 5.2, I have a model using has_many_attached :images. I would like to send out an email that includes all associated images as attachments.
My mailer method currently looks like:
def discrepancy_alert(asset_discrepancy_id, options={})
#asset_discrepancy = AssetDiscrepancy.find asset_discrepancy_id
#asset_discrepancy.images.each_with_index do |img,i|
attachments["img_#{ i }"] = File.read(img)
end
mail to: 'noone#gmail.com', subject: "email subject"
end
obviously, File.read does not work here because img is not a path, it is a blob. I have not been able to find any info on this in the docs
Question One:
Is there a rails method for attaching a blob like this?
I can use the following instead:
#asset_discrepancy.images.each_with_index do |img,i|
attachments["img_#{ i }"] = img.blob.download
end
Question Two:
the download method could use a log of RAM, is this usage ill advised?
It seems, with the addition of ActiveStorage, that rails mailers would have some new methods for interaction between the two....I have not seen anything in the docs. All the mailer attachments[] examples use paths to a local file.

Answer 1

in app/mailers/mailer.rb:
if #content.image.attached?
#filename = object.id.to_s + object.image.filename.extension_with_delimiter
if ActiveStorage::Blob.service.respond_to?(:path_for)
attachments.inline[#filename] = File.read(ActiveStorage::Blob.service.send(:path_for, object.image.key))
elsif ActiveStorage::Blob.service.respond_to?(:download)
attachments.inline[#filename] = object.image.download
end
end
in mailer view:
if #filename
image_tag(attachments[#filename].url)
else
image_tag(attachments['placeholder.png'].url)
end

Answer 2

This worked for me in production using Amazon S3.
in mailer view:
if #object.images
#object.images.each do |image|
path = "https://www.example.com" + Rails.application.routes.url_helpers.rails_blob_path(image, only_path: true)
<img src="<%=path%>">
end
end

Answer 3

Here is the working solution for active storage url in email template. I have seen the images visible in gmail. You can use "rails_blob_url". This works for file stored in aws s3.
mailer.rb
....
#image_url = Rails.application.routes.url_helpers.rails_blob_url(blob),
....
mailer view file
<img src="<%= #image_url %>">