Rails 3 Wicked PDF - include Paperclip S3 pdf files - ruby-on-rails

Question

I have a Rails 3 app that uses these gems:
gem 'paperclip'
gem 'wicked_pdf'
gem 'combine_pdf'
I'm using wicked_pdf to open a pdf for a costproject. The costproject has an HTML page called viewproject.pdf.erb.
I'm trying to combine the wicked pdf with the costproject attachments into a single pdf.
This is my controller code:
def viewproject
#costproject = Costproject.find(params[:costproject_id])
respond_to do |format|
format.html
format.pdf do
pdf = CombinePDF.new
pdf2 = render_to_string pdf: "Costproject.pdf", template: "costprojects/viewproject", encoding: "UTF-8"
pdf << CombinePDF.new(pdf2)
#costproject.attachments.each do |attachment|
pdf << CombinePDF.new(attachment.attach.path)
end
send_data pdf.to_pdf, :disposition => 'inline', :type => "application/pdf"
end
end
end
The line pdf << CombinePDF.new(pdf2) is giving me:
string contains null byte
If I look at pdf2, it starts like this - so it looks like a pdf:
>> pdf2
=> "%PDF-1.4\n1 0 obj\n<<\n/Title (\xFE\xFF)\n/Producer (wkhtmltopdf)\n/CreationDate (D:20150405202628)\n>>\nendobj\n4 0 obj\n<<\n/Type /ExtGState\n/SA true\n/SM 0.02\n/ca 1.0\n/CA 1.0\n/AIS false\n/SMask /None>>\nendobj\n5 0 obj\n[/Pattern /DeviceRGB]\nendobj\n8 0 obj\n<<\n/Type /XObject\n/Subtype /Image\n/Width 71\n/Height 75\n/BitsPerComponent 8\n/ColorSpace /DeviceRGB\n/Length 9 0 R\n/Filter
I also tried pdf << CombinePDF.new(pdf2.to_pdf)
Thanks for the help!
UPDATE1
As a test, to see if pdf2 is working, I did this successfully:
def viewproject
#costproject = Costproject.find(params[:costproject_id])
respond_to do |format|
format.html
format.pdf do
pdf2 = render_to_string pdf: "Costproject.pdf", template: "costprojects/viewproject", encoding: "UTF-8"
send_data pdf2, :disposition => 'inline', :type => "application/pdf"
end
end
end
UPDATE2
Myst was correct about using parse. Thanks!
I am now using this line in the controller code:
pdf << CombinePDF.new(attachment.attach.url)
I get this error:
No such file or directory - http://s3.amazonaws.com/ ...
But, if I copy the http address and paste into the browser the pdf shows up.

Answer 1

I am editing this answer to reflect the issue of remotely stored PDF files.
I should point out that without a persistent connection to the S3 storage and without using the S3 API, the following solution WILL effect performance*.
As I pointed out, the CombinePDF.new method is the same as the CombinePDF.load method. It accepts a file name and attempts to open the file. The CombinePDF.parse method will accept raw PDF data and parses it into a PDF Object.
In the following code I use Net::HTTP.get(URI.parse(url)) to get the raw PDF data.
I recommend replacing this solution with a S3 native solution, so that the whole application can share one or more persistent connections. This is a performance issue that may or may not be important for you.
require 'net/http'
def viewproject
#costproject = Costproject.find(params[:costproject_id])
respond_to do |format|
format.html
format.pdf do
pdf = CombinePDF.new
pdf2 = render_to_string pdf: "Costproject.pdf", template: "costprojects/viewproject", encoding: "UTF-8"
pdf << CombinePDF.parse(pdf2)
#costproject.attachments.each do |attachment|
pdf << CombinePDF.parse( Net::HTTP.get( URI.parse( attachment.attach.url ) ) )
end
send_data pdf.to_pdf, :disposition => 'inline', :type => "application/pdf"
end
end
end
* The performance hit is dependent on the amount of PDF attachments you have, on the number of users your app has, on network traffic, on your framework (single/multi-thread) and other factors.
A persistent connection should reduce the performance hit in a dramatic way, mainly due to the fact that establishing connections is an expensive action.