高階示例

這是帶有示例的高階方法

class FundsController < ApplicationController

  def index
    @funds = Fund.all_funds(current_user)
  end

  def show
    @fund = Fund.find(params[:id])
    respond_to do |format|
      format.html
      format.pdf do
        pdf = FundsPdf.new(@fund, view_context)
        send_data pdf.render, filename: 
        "fund_#{@fund.created_at.strftime("%d/%m/%Y")}.pdf",
        type: "application/pdf"
      end
    end
  end
end  

我上面的程式碼我們有這條線 FundsPdf.new(@fund, view_context)。這裡我們用 @fund 例項和 view_context 初始化 FundsPdf 類，以在 FundsPdf 中使用輔助方法。FundsPdf 看起來像這樣

 class FundPdf < Prawn::Document

  def initialize(fund, view)
    super()
    @fund = fund
    @view = view
    upper_half
    lower_half
  end

  def upper_half
    logopath =  "#{Rails.root}/app/assets/images/logo.png"
    image logopath, :width => 197, :height => 91
    move_down 10
    draw_text "Receipt", :at => [220, 575], size: 22
    move_down 80
    text "Hello #{@invoice.customer.profile.first_name.capitalize},"
  end

  def thanks_message
    move_down 15
    text "Thank you for your order.Print this receipt as 
    confirmation of your order.",
    :indent_paragraphs => 40, :size => 13
  end
end 

這是使用 Prawn gem 生成 PDF 的最佳方法之一。