#153 PDFs with Prawn (revised)

Nov 03, 2011 | 11 minutes | Plugins

Prawn is an excellent Ruby library for generating PDF documents. Here you will learn how to add it to a Rails application through a separate PDF renderer class.

Click to Play Video ▶

Download:
source codeProject Files in Zip (87.2 KB)
mp4Full Size H.264 Video (25.1 MB)
m4vSmaller H.264 Video (13.1 MB)
webmFull Size VP8 Video (15.3 MB)
ogvFull Size Theora Video (30.2 MB)

Enrico Carlesso about 13 years ago

Hi Ryan,
as always a very useful screencast! But here the hard question:

How do you test things like this?

debprado about 13 years ago

capybara-prawn?

just joking :)

James Healy almost 13 years ago

Ryan's suggested approach makes testing PDFs a breeze.

Create a new unit spec for the OrderPdf class and focus on the #render() method.

As a simple first step, spec that the render() methods returns a string that starts with "%PDF" to make sure it's generating a PDF.

To improve the specs, I'd check the PDF contains the appropriate text.

pdf    = OrderPdf.new
reader = PDF::Reader.new(StringIO.new(pdf.render))
page   = reader.page(1)

page.should include("order #1")

Nicolai Seerup over 10 years ago

maybe this : https://github.com/prawnpdf/pdf-inspector

Nik about 13 years ago

Hi there, I am still rather new to programming. I at around 4:50 where Ryan says something about you can either have the orderpdf class inherit from prawn::document or something about delegating? I know it may be too long to explain here, but does anyone know of a good place to start looking? I don't know even what keyword to search on google about this..

Thank you!

Keith Thibodeaux about 13 years ago

I'm honestly not too familiar with the concept myself. After I watched the video I had the same curiosity. Found this: http://www.simonecarletti.com/blog/2009/12/inside-ruby-on-rails-delegate/

Hope it helps =]

Ryan: great screencast as always, I've been wanting to see an updated version of this one for a while :D

Nik about 13 years ago

Oh wow, thanks for the find!

Matthieu Guillemot about 13 years ago

In this case, I think Ryan just suggested you would use a Prawn::Document object inside your OrderPdf class, instead of inheriting from it. So for example, you would change:

          ruby
        
class OrderPdf < Prawn::Document
  def initialize
    super
    text "Order goes here"
  end
end

into:

          ruby
        
class OrderPdf
  def initialize
    @pdf = Prawn::Document.new
    @pdf.text "Order goes here"
  end

  def render
    @pdf.render
  end
end

(or use the delegate method mentionned by syath instead of writing your own render method)

In general, prefer composition to inheritance is considered good engineering practice because you control more tightly what your class exposes when you "use" an object rather than inheriting from it, so you have less surprises in the future.

For example, if a new version of Prawn renames the render function to render_document, you can just modify your own render method to use the new render_document one, instead of having to track every usage of render in your application. Or if you want to scrap Prawn and use another library, you can probably just modify your OrderPdf without rewriting a single line outside of it.

That's what we mean when we say that composition offer better encapsulation than inheritance.

Joel over 12 years ago

Enlightening. Thanks for the post!

Kurt Mueller over 11 years ago

Thanks for this awesome post.

debprado about 13 years ago

Any tips on how to test the content of the pdf?

Forrest Zeisler about 13 years ago

I've actually forked off prawnto and merged all the fragmented branches into a gem. It's working well with Rails 3.1. I hope to continue development, so don't be shy about feature requests or contributions.

You can find it at https://github.com/forrest/prawnto

Gabriel over 12 years ago

Great I'll check it out!

Do you know how can I send a pdf generated with prawn as an attachment in an email? Want to send invoices when a customer buys something.

Would really appreciate any help!!!

sbuhr about 13 years ago

Hey everyone,

does anyone got :rowspan and/or :colspan working? I've installed the prawn-layout gem and tried this -> (https://github.com/blaxter/prawn-layout/blob/3a80fa65d7c06774c615d6f64b5d24a4a2af784f/examples/table/table_rowspan.rb) example, but nothing happens.

I really want to use prawn, but i really need colspan and rowspan.

Thanks.

dthstr almost 13 years ago

The episode video doesn't work (always "Loading...") -- I've also tried to download the mp4 file but get a "404 Not Found"...

Oliver Kriška almost 13 years ago

I set up template, but it's only on first page, can you help me?

          ruby
        
def initialize(....)
super(:template => filename,:bottom_margin => 120)

Billy Forester almost 13 years ago

I'm having an issue getting font color to work. I have the code below in my OrderPdf class I recieve no errors but it never changes the color, any ideas?

          ruby
        
text "#{@agenda.customer.name.titleize} - Weekly Conference Call", :align => :center, :size => 25, style: :bold, :color => "0000FF"

Nick Romanowski almost 13 years ago

This functionality was added after the last gem release 0.12.0, if you want to use the latest release you can use the github version by adding the following in your Gemfile:

          ruby
        
gem "prawn", :git => "git://github.com/sandal/prawn.git"

Florian Görlitz almost 13 years ago

In ASCII cast there is a '=' missing between self.row_colors AND ["DDDDDD","FFFFFF"]

BTW
Great Cast!!!

Mark Kremer almost 13 years ago

Thanks for reporting that! The ASCIIcast has been corrected.

J. Mark Locklear over 12 years ago

I'm wondering if anyone has ideas on turning a custom page into a pdf. I have a search page. I have a custom action in my controller that looks like this..

          ` ruby
        
   def search
    from_date = Date.new(params[:from_date][:year].to_i, params[:from_date][:month].to_i, params[:from_date][:day].to_i).to_s(:db)
    to_date = Date.new(params[:to_date][:year].to_i, params[:to_date][:month].to_i, params[:to_date][:day].to_i).to_s(:db)
    @visits = Visit.search(from_date, to_date, current_user)
      respond_to do |format|
        #format.html # show.html.erb
        format.pdf do
          pdf = Prawn::Document.new
          pdf.text @visits
          send_data pdf.render
        end
      end
  end

When I do this I get a "Completed 406 Not Acceptable". I've also tried to add a link_to to my view, and I get a different issue there. I've laid that out here. http://stackoverflow.com/questions/9381244/rails-3-passing-date-params-to-url Any help appreciated.

F. Barry Knotts over 12 years ago

Great cast. It's just what I needed.

However, I've had a surprise issue. I followed the video closely. My development environment functioned flawlessly (MacBook Pro, ruby 1.9.2-p290, rails 3.1.3). When loaded into my production server (Intel motherboard, Ubuntu 11.10, ruby 1.9.2-p290, rails 3.1.3) the call to the pdf class from my controller fails with an "uninitialized constant PatientsController::PatientsPdf" It's as though the internal rails "path" fails to find the file in the /app/pdfs directory. I could load the pdf class definition into my controller, but that's going to be a little messy. Any suggestions?

F. Barry Knotts over 12 years ago

Rookie error!

I discovered the problem.

I had capitalized the first letter of the _pdf.rb files in the app/pdfs directory. Worked OK on the MAC. Completely confused Ubuntu.

Daniel Eißing over 12 years ago

Great cast. This was extremely helpful, as always. Thanks for this.

I have still one question, though: Now after I've created my PDF through Prawn, how would I go about caching the PDF? Has anyone any experience with this?

Jon Waghorn over 12 years ago

I did this recently. On first create rendered the pdf to webserver's filesystem (/public/generated_docs or similar). In future check for existence of the generated file and render a link to it rather than a link to generate the pdf.

If you don't have too many pdfs then you could pre-render all of them. Depends on your web app if this is suitable or not.

Gabriel over 12 years ago

Great cat as always, very helpful!

Does anyone know how to send a pdf generated with prawn as an attachment? I've search for docs on this and can't find any.

Gabriel over 12 years ago

typo: *cast

Gabriel over 12 years ago

Found a solution to send a prawn generated pdf as an email attachment. Inside your mailer:

def new_subscription(user, invoice) @invoice = invoice pdf = SubscriptionPdf.new(@invoice) attachments["invoice.pdf"] = { :mime_type => 'application/pdf', :content => pdf.render } mail(:to => user.email, :subject => 'Subscription Receipt', :from => "example@example.com") end

This is working for me on Rails 3.2

Steve Christie about 12 years ago

Thanks for this. Just what i was looking for. Works perfectly.

Carlos over 9 years ago

Thanks. Works perfectly for me as well. To who ever uses this method, don't forget to render the pdf as I hadn't first time round and crashed my browser...

Scott over 12 years ago

I got Prawn working, but I keep getting this message in my terminal:

mime_type.rb:102: warning: already initialized constant PDF

Anyone else have this issue?

Gabriel over 12 years ago

Yes I have the same issue, although everything is working fine and it does not appear to be affecting anything (to my knowledge). Just an annoying message hopefully...

mfueger over 12 years ago

Same issue here. What's more, removing the register statement from mime_types.rb may break your app in production.

bakki over 12 years ago

I know it has been several months, but I get the same msg but doesn't seem to hurt anything in production. I'd just like to stop if from annoying me every time I do a rails s or c. Any progress on the issue?

MrHubble about 12 years ago

The pdf mime type is added by default in Rails 3.2: http://edgeguides.rubyonrails.org/3_2_release_notes.html

So you no longer need to tell Rails about the PDF MIME type with the following line:Mime::Type.register "application/pdf", :pdf

dirk grandjean over 12 years ago

Maybe a strange question but, how would I be able to create for example two pdf files of the same show page?
For example, one pdf file would create an overview and one pdf file would go more into detail, is this possible with prawn?

Many thanks!

dirk grandjean over 12 years ago

I generated a new page and will try to use this as solution. ;)

Geoffplewis over 12 years ago

Such a great episode! Thanks!

CodisaIT over 12 years ago

I'm trying this line

          ruby
        
pdf = OrderPdf.new(@order, view_context)

but I get this error "SyntaxError in xxxController#index"
syntax error, unexpected ',', expecting ')'

I get this error when adding the "view_context"

I'm using rails 3.2.5

Alexander Farley almost 12 years ago

disposition: "inline" isn't working in Chrome for me. This appears to be somewhat of a known problem with Chrome, something related to Chrome not knowing the file type and deciding not to render it. It works fine in Firefox. Does anybody know a fix?

Update: removing the Mime configuration line seemed to fix this problem. This is using Rails 3.2.1.

Ender almost 12 years ago

What about utf-8? I cannot see Turkish characters in pdf file :/

Andy Sze almost 12 years ago

prawn already support utf-8,just import your font file.

Pieter Gunst almost 12 years ago

I'm having trouble moving the code that generates the pdf from the controller to a separate ruby file.

I have the following code in the relevant part of my controller:

def show
@corporation = Corporation.find(params[:id])

respond_to do |format|
  format.html # show.html.erb
  format.json { render json: @corporation }
  format.pdf do
    pdf = CertificatePdf.new
    send_data pdf.render, type: "application/pdf", disposition: "inline"

I created a separate certificate_pdf.rb file in the folder app/pdfs which contains the following code:

class CertificatePdf < Prawn::Document
    def intitialize
        super
        text "Help"
    end
end

However, when I open the generated pdf the document is blank. Any thougths?

Vamsi almost 12 years ago

Thanks !

Tom Caflisch almost 12 years ago

The filename is not getting set using your method. Is there a different way to set the filename?

David Ortiz Frau over 11 years ago

Prawn is working fine in development but in production, my app is not even opening. When I check production logs I get a looping message

          production.log
        
...
19x.xxx.xxx.xxx: Connecting to database specified by database.yml
19x.xxx.xxx.xxx: Connecting to database specified by database.yml
19x.xxx.xxx.xxx: Connecting to database specified by database.yml
19x.xxx.xxx.xxx: Connecting to database specified by database.yml
...

David Chmura almost 11 years ago

Did you ever find an answer?

David Van Der Beek over 11 years ago

Does anyone know how to get a background image working when following this methodology? I tried setting it in the controller and in the PDF class where the margins get set. The only thing I can get to work is adding an image the full size of the page, but if I try to repeat that using Prawn's repeat method, the image covers up all the content on the pages. I can't add the image manually one page at a time because the length of the content determines how many pages there are.

David Chmura almost 11 years ago

Did you ever find an answer?

Michael Moulsdale over 11 years ago

Great article. I've been using this for a while and due to the number of PDFs that I create would like to create one or more 'partials' or similar to share standard methods (company address, header info etc.). Has anyone been able to do this. There are some queries that allude to this on Stack overflow, bu they are all quite old and don't use the pdfs folder

Teddy Widom over 10 years ago

Prawn had support for 'templates' removed in recent versions. The only solution I know of is to put shared content into helper modules, then mix those modules into each class that you need them in.

I wrote a short example of how to do this here

Kyle Keesling about 11 years ago

Just did a little write-up which goes over how to add a repeating footer to your PDFs using Prawn - http://kyleke.es/posts/2013/11/creating-a-repeating-footer-w-prawn/

twdeveloper over 10 years ago

Does anyone have an example they could post that lists all of the projects, like in index.html.erb, instead of just 1 project (like the tutorial using #show).

Thank You.

Frank004 almost 10 years ago

Looking for a way to add to my Table a remote image from s3 to my prawn pdf.

otagi almost 10 years ago

I'm using this to insert an S3 image into a table cell:

          ruby
        
class CustomPdf < Prawn::Document
  require 'open-uri'

  def image_cell(image_url)
    {image: open(image_url), fit: [IMAGE_SIZE, IMAGE_SIZE], position: :center}
  rescue SocketError
    ""
  end
end

Then just call image_cell in your table data array: [ [ image_cell(url), ... ], [ ... ] ].

Frank004 almost 10 years ago

Hi otagi I get this error OpenURI::HTTPError 403 Forbidden

          
        
def inspections_rows
    [['Porciento','Inspección','Fecha','Gerente',{:content => "Cliente", :colspan => 2},'Cantidad de Áreas']] +
      @inspections.map do |inspection|
       [percentage(inspection.inspection_score),inspection.name, inspection.date,inspection.manager,inspection.client,
       image_cell(inspection.client_sign(:small).to_s.sub!(/\?.+\Z/,'')),inspection.inspection_sections.count]

    end
  end

  def image_cell(image_url)
    {image: open(image_url), fit: [IMAGE_SIZE, IMAGE_SIZE], position: :center}
  rescue SocketError
    ""
  end

Frank004 almost 10 years ago

Thank you works!! now

Ben Koshy about 9 years ago

hi folks, I am getting an: "uninitialized constant QuoteController::Prawn" error.

at the following line (with the code in the relevant controller):

                    format.pdf do
---> here --->  pdf = Prawn::Document.new

anybody have any ideas? It's giving me grief!

bparanj over 8 years ago

This episode has been updated to Rails 5 as a blog post PDFs with Prawn in Rails 5

MuhammadRazaAslam over 7 years ago

I want to add before_filter :authenticate_user! but it throws an error.Can you tell you me how i can do this?

StevenChamberlain over 7 years ago

Good Post