Reorder Multiple Elements ala Netflix

gistfile1.rb

    images = @album.image_assignments

    changed = Array.new

    # Get the images that changed order
    for image in images
      order = params["order_#{image.image_id}".to_sym]
      if !order.blank? && order =~ /^\d+$/ && image.position.to_i != order.to_i
        image.position = order.to_i
        changed << image
      end 
    end 

    # Resort based on new position
    changed.sort! { |a, b| a.position <=> b.position }

    # Remove the changed images
    for image in changed
      images.delete_if { |a| a.id == image.id }
    end 

    # Reinsert the changed images
    for image in changed
      images.insert(image.position - 1, image)
    end 

    idx = 1 

    # Reindex all positions, only saving what actually changed
    for image in images.compact
      image.position = idx 
      image.save if image.position_changed?
      idx += 1
    end