this is some code that generates a csv for amazon and uses a Resque task so it runs in the background

product_gen.rb

class Spree::Admin::AmazonProduct < ActiveRecord::Base
  attr_accessible :Description, :FileName, :Title, :template

  @queue = :amazon_products

  def self.perform(id,filename,site)
	
	puts "#{Time.now}"
  	start_time = Time.now
  	puts "loading products..."
	
	prods = Spree::Product.where("count_on_hand > ?",0)
  	
  	puts "loaded #{prods.count} products processing....."


	File.open("#{Rails.public_path}/#{filename}.csv", 'w+') {|f| 

		f.write("\"short_description\",\"description\",\"sku\",\"categories\",\"product_id\",\"price\",\"qty\",\"manufacturer\",\"image\"\n")
		prods.each_with_index {|p,i| 

  			f.write(fill_template(p,"www.kingsfieldcomputers.co.uk"))
  			puts "#{prods.count}/#{i}: #{p.sku}"
  		}
	}
  	end_time = Time.now

  	puts "This task ran from #{start_time} - #{end_time}"
  end


  def self.fill_template(product,site)

  	template = "\"{short_description}\",\"{description}\",\"{sku}\",\"{categories}\",\"{product_id}\",\"{price}\",\"{qty}\",\"{manufacturer}\",\"{image}\"\n"


	template = template.gsub("{url}", "http://#{site}/products/" + product.permalink) if template.include? "{url}"
	template = template.gsub("{short_description}", product.name) if template.include? "{short_description}"
	template = template.gsub("{description}", product.description) if template.include? "{description}"
	template = template.gsub("{sku}", product.sku) if template.include? "{sku}"
	if product.taxons.first.nil?
		template = template.gsub("<g:product_type>{categories}</g:product_type>", "") 
	else
		template = template.gsub("{categories}", product.taxons.first.id.to_s) if template.include? "{categories}"
	end
	template = template.gsub("{price}", (product.price * 1.08).to_s) if template.include? "{price}"
	template = template.gsub("{product_id}", product.id.to_s) if template.include? "{product_id}"
	template = template.gsub("{qty}", product.count_on_hand.to_s) if template.include? "{qty}"
	template = template.gsub("{manufacturer}", product.name) if template.include? "{manufacturer}"
	if !product.icecat.nil? 
		template = template.gsub("{image}", "http://images.icecat.biz/thumbs/#{product.icecat}.jpg") if template.include? "{image}"
	else
		template = template.gsub("{image}", "") if template.include? "{image}"
	end

  end
end