"I want to use ActiveScaffold, and allow me to upload files to the server, but these files are documents and then I want to be able to click "import" on each entry and with AJAX show EACH document individually being processed in the background with the percentage complete auto updating on the screen. This has to work for any number of files and each process needs to run independently of the others. Oh... also, if the person leaves the site and comes back later and clicks "import" again, it should show where it is up to, not start a new import."

1. Have a working How to Install Ruby on Rails


2. Get BackgroundRB


3. Get Get ActiveScaffold


4. Make a model:
db/migrate/create_documents.rb


class CreateDocuments < ActiveRecord::Migration
  def self.up
    create_table :documents do |t|
      t.column :title, :string
      t.column :created_at, :datetime
      t.column :updated_at, :datetime
      t.column :imported, :boolean
      t.column :job_key, :string
      t.column :progress, :integer
    end
  end

  def self.down
    drop_table :documents
  end
end



5. Turn on ActiveScaffold for the Document page and make an "import" button in Active Scaffold:
app/controllers/documents_controller.rb


class DocumentsController < ApplicationController
  active_scaffold :document do |config|
  config.action_links.add 'import', :label => 'Import',
                                        :type => :record,
                                        :method => 'put'
  end
end



6. Make a controller that will call the worker:
app/controllers/documents_controller.rb


def import
 if request.xhr?
   @document = Document.find(params[:id])
   unless (@document.imported == true)
     if ((@document.job_key == nil || ""))
       job_key = "#{Time.now.to_i}-DOC#{@document.id}"
       MiddleMan.new_worker(:class => :book_import_worker,
                            :args => {:document_id => @document.id,
                            :job_key => job_key},
                            :job_key => job_key)
       @document_id = @document.id
     end
   end
 end
end 



7. Make the worker you are going to call:
lib/workers/book_import_worker.rb


class BookImportWorker < BackgrounDRb::Rails
  def do_work(args)
    # Setup the job
    @document = Document.find_by_id(args[:document_id])
    @document.job_key = args[:job_key]
    @document.imported = false
    @document.save!
    @logger.info("Book import started on Document Job Key #{args[:job_key]}")
    # Initialize progress variable and total (set total to
    # how much you want progress to get to)
    @progress = 1
    @total = 200
    # Do some work
    while @document.progress < @total
      progress(1)
      # Do work.....
      sleep 2
    end
    # Clean up after yourself and set the document to being done
    @document.job_key = nil
    @document.imported = true
    @document.progress = 100
    @document.save!
    kill()
  end
  private
    # progress method to update the document
    def progress(p)
    @progress += p
    # Get the percentage complete
    @result = (@progress.to_f / @total) * 100
    # Sanitize it in case you are wrong on the "total estimate"
    @result = 1 if @result < 1
    @result = 100 if @result > 100
    # Print this to the log - you can watch it happening with
    # $RAILS_ROOT/tail -f log/backgroundrb.log
    @logger.info("Worker job_key: #{@document.job_key}, 
       total is: #{@total}, Progress is: #{@progress}, 
       Percentage done is #{@result}")
    # Save the progress
    @document.progress = @result.to_i
    @document.save!
  end
end



8. Make the importing page:
app/views/documents/import.rhtml
For some reason the editor is parsing my escaped HTML as real HTML!
So I have bundled it all up here.


9. Make the get status "ping" method in the controller:
app/controllers/documents_controller.rb


def ping
  @document = Document.find(params[:id])
  @percent = @document.progress
  @document_id = @document.id
  redirect_to :action => :index unless request.xhr?
end



10. Make the ping.rjs file
app/views/documents/ping.rjs


page.replace_html("progressbar#{@document_id}", 
                    :partial => "percent",
                    :object => @percent)

# If the percentage is equal to or over 100... 
# then replace it with a nice # finished partial. 
# Note, there is some trickery here, you need to
# ADD a SECOND element that has the ID 
# "#{@document.id}indicator" and make it
# hidden somewhere in the page 
# otherwise the periodically_call_remote will
# continue looking for it when you
# close the active scaffold view.  
#It is a pain in the butt. 
if @percent >= 100
  page.replace_html("progressbar#{@document_id}", 
                     :partial => "finished", 
                     :object => @percent)
  page.insert_html(:after, "documents-active-scaffold",
                     :partial => "finished_hidden")
end 



11. Make the progress bar partial:
app/views/documents/_percent.rhtml
It is all in here.


12. Make the finished bar partial:
app/views/documents/_finished.rhtml
Same file here.


13. Make the hidden finished bar
app/views/documents/_finished_hidden.rhtml
Here it is again.


14. Press PLAY!

One day I'll do a screen cast... :) for now, you'll have to take my word for it that it looks really cool.

There you go!

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Mikel