Unable to render PDF to browser using Prawn PDF for Ruby on Rails

Question

I am creating a pdf file in the latest version of the Prawn library (v1.0.1rc) in Rails (3.1.1) and when I run my code it generates the PDF into the root of the application.

I don't want this. I want it to render the output into user's browser window, without saving it locally to the server.

Please tell me how I can achieve this. Here are my files:

views/foo/show.pdf.erb:

<%=

require 'prawn'

pdf = Prawn::Document.new(:page_size => 'LETTER', :page_layout => :landscape, :margin => 50, :top_margin => 20, :bottom_margin => 50)

.....

render_file("foo.pdf")

%>

controllers/foo_controller:

class AuditsController < ApplicationController
  before_filter :authenticate_user!
  layout 'application'
  can_edit_on_the_spot
  respond_to :html, :xml, :js, :pdf

  def index
    @audits = Audit.all
    respond_with @audits
  end

  def show
    @audit = Audit.find(params[:id])
    respond_with @audit do |format|
      format.pdf { render :layour => false }
    end
  end

Answer 1

Gemfile

gem 'prawn'

/config/initializers/mime_types.rb

Mime::Type.register "application/pdf", :pdf

AuditsController

def show
  @audit = Audit.find(params[:id])
  respond_to do |format|
    format.html
    format.pdf do
      pdf = Prawn::Document.new
      pdf.text "This is an audit."
      # Use whatever prawn methods you need on the pdf object to generate the PDF file right here.

      send_data pdf.render, type: "application/pdf", disposition: "inline"
      # send_data renders the pdf on the client side rather than saving it on the server filesystem.
      # Inline disposition renders it in the browser rather than making it a file download.
    end
  end
end

I used to use the prawnto gem before Rails 3.1, but it doesn't work without a bit of hacking anymore. This is a much cleaner way to instantiate and display the PDF object in 3.1 by accessing Prawn directly.

I got this technique straight from one of Ryan Bates' Railscasts. Been using it ever since. You can view that specific episode here. He goes into much more detail about subclassing Prawn and moving the PDF generating code out of the controller. Also shows a lot of useful Prawn methods to get you started. Highly recommended.

A lot of the episodes are free, but that revised Prawn episode is one of those that are only available with a paid subscription. At $9/month though, a subscription quickly pays for itself.

Answer 2

I find the best way to send a pdf to the client's browser is to put the download into a link. Often you need to generate a pdf after form submission, but also need to redirect to another page.

You can't redirect and send the pdf simultaneously, but you can redirect and then provide a download link, like so:

First add gem 'prawn' to your gemfile. Bundle. Then do the following:

Link to your special printing action in your view

<%= link_to 'print ticket', print_ticket_path %>

route to special printing action in routes.rb

match 'print_ticket', to: 'tickets#print_ticket'

action that sends the outputted file (change per your needs):

  def print_ticket
    if session[:token]
      @pdf = generate_pdf(session[:token])
      send_data(@pdf, :filename => "output.pdf", :type => "application/pdf")
    end
  end

  private 
  def generate_pdf(token)
    Prawn::Document.new do
        formatted_text [ { :text=>"xxx.org", :styles => [:bold], :size => 30 } ]
        move_down 20
        text "Please proceed to the following web address:" 
        move_down 20
        text "http://xxx.org/finder"
        move_down 20
        text "and enter this code:"
        move_down 20
        formatted_text [ { :text=>token, :styles => [:bold], :size => 20 } ]
    end.render 
  end