How to update the database when users download an ActiveStorage blob attachment?

Question

Currently users can download an ActiveStorage blob in my app using the following link:

link_to 'download', rails_blob_path(pj.document.file, disposition: 'attachment')

However, I would like to update an attribute in the database for the associated model to register when the file was first downloaded. This field is called the downloaded_at field.

I have made the following attempt:

1. Changed the link_to > button_to as I'm updating the model.
2. Added the appropriate route

3. Added the following code in the database:

   def download
       @proofreading_job = ProofreadingJob.find(params[:id])
       @proofreading_job.update(downloaded_at: Time.current) if current_user == @proofreading_job.proofreader.user
       response.headers["Content-Type"] = @proofreading_job.document.file.content_type
       response.headers["Content-Disposition"] = "attachment; #{@proofreading_job.document.file.filename.parameters}"
   
       @proofreading_job.document.file.download do |chunk|
         response.stream.write(chunk)
       end
       ensure
       response.stream.close
   end
   

However, this does not do anything except redirect to the @proofreading_job page which is not what I want.

Has anyone done this before and if so how can I accomplish this task.

Answer 1

In the end I just used some javascript to capture the click of the button as follows:

    td = link_to rails_blob_path(pj.document.file, disposition: 'attachment'), 
         id: pj.document.id, 
   download: pj.document.file_name, 
      class: "btn btn-outline-secondary btn-sm btn-download" do
        =pj.document.file_name 
        i.fa.fa-download.ml-3 aria-hidden="true"

coffee script:

  $('.btn-download').on 'click', (e) ->
    id = $(this).attr('id')
    $.ajax {url: Routes.document_path(id), type: 'PUT'}

routes.rb

resources :documents, only: [:show, :update]

documents_controller.rb:

  def update
    document = Document.find(params[:id])
    authorize([:proofreaders, document]) 
    document.update(downloaded_at: Time.current) if document.downloaded_at.nil?
    head :ok
  end

This seems to work very well. It updates the database and the user gets the file downloaded to their computer.