## error
 NoMethodError in InvoicesController#print

You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.each
lib/invoice_drawer.rb:58:in `draw'
lib/invoice_drawer.rb:36:in `new'
lib/invoice_drawer.rb:36:in `draw'
app/controllers/invoices_controller.rb:81:in `print'

## /lib/invoice_drawer.rb
class InvoiceDrawer
def self.draw(invoice)
  pdf = PDF::Writer.new(:paper => "A4")
    pdf.select_font "Times-Roman"
    pdf.text("Page One Technologies Pty. Ltd.", :font_size => 16, :justification => :left)
    pdf.text("A.B.N 85 074 597 103", :font_size => 8, :justification => :left)
    pdf.text("Suite 4, No. 1 Shaw Road", :font_size => 10, :justification => :left)
    pdf.text("Ingleburn NSW 2565", :font_size => 10, :justification => :left)
    pdf.text("Ph: (02) 9829 3151 Fax: (02) 9829 2713", :font_size => 10, :justification => :left)
	pdf.text("\n")
	pdf.text("Job/Invoice ##{"%05.0f" % invoice.id}", :font_size => 10, :justification => :right)
    PDF:: SimpleTable.new do |billto|
      billto.column_order.push(*%w(billto))

	  billto.columns["billto"] = PDF::SimpleTable::Column.new("billto") { |col|
	   col.heading = "BILL TO"
	  }
	   billto.show_lines       = :outer
	   billto.show_headings    = true
       billto.position         = :left
	   billto.orientation      = 20
	   billto.shade_rows	   = :none
	   billto.width			   = 170
	   data = [
	     { "billto" => "#{invoice.client.name}" },
		 { "billto" => "#{invoice.client.address}" },
		 { "billto" => "#{invoice.client.suburb} #{invoice.client.state} #{invoice.client.postcode}" }
		 ]

        billto.data.replace data
        billto.render_on(pdf)

	 pdf.text("\n")

      end
	  PDF:: SimpleTable.new do |invoice|
      invoice.column_order.push(*%w(description quantity rate amount))

	  invoice.columns["description"] = PDF::SimpleTable::Column.new("description") { |col|
	   col.heading = "Description"
	  }
	  invoice.columns["quantity"] = PDF::SimpleTable::Column.new("quantity") { |col|
	   col.heading = "Quantity"
	  }
	  invoice.columns["rate"] = PDF::SimpleTable::Column.new("rate") { |col|
	   col.heading = "Rate"
	  }
	  invoice.columns["amount"] = PDF::SimpleTable::Column.new("amount") { |col|
	   col.heading = "Amount"
	  }
	   invoice.show_lines       = :outer
	   invoice.show_headings    = true
       invoice.position         = :left
	   invoice.orientation      = 20
	   invoice.shade_rows	    = :none
	   invoice.width		    = 792


    !! I recommend this goes in your controller to stop slowing down your pdf exporting.
    @activities = @invoices.activities.find(:all)

    data = @activities.collect do |o|
        	     { "description" => "#{o.comments}", "quantity" => "#{hour_format(o.minutes)}", "rate" => "#{number_to_currency(o.rate)}" }, "amount" => "#{number_to_currency(o.price)}"}
	   end

        invoice.data.replace data
        invoice.render_on(pdf)
		end
		end
	  pdf.render

end
end

## invoices_controller.rb
  def print
  @invoice = Invoice.find(params[:id])
  send_data InvoiceDrawer.draw(@invoice), :filename => 'invoice.pdf', :type => 'application/pdf', :disposition => 'inline'
  end