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Usually I would use an HTML-to-PDF library to to generate and display a PDF.
An absolutely different , alternative way to view or download a page as PDF would be via a headless browser API.
Gem Ferrum lets you open a headless chrome browser and perform different actions (click link, take screenshot, open as PDF, etc.)
Why not use Ferrum to open or save a file as PDF?
Here’s how it could work:
Example of an HTML page ⤵️
Clicking the “View as PDF” link would open a link as PDF ⤵️
Install and use Gem Ferrum
Install the gem:
# Gemfile
gem "ferrum"
Add a route:
# config/routes.rb
get 'home/index'
Add an HTML page.
You can add a link_to render the page as PDF.
Notice I add a class .no-print, so that the link does not get displayed in print media type.
<!-- app/views/home/index.html.erb -->
<h1>Home#index</h1>
<p>Find me in app/views/home/index.html.erb</p>
<div class="no-print">
<%= link_to "View as PDF", home_index_path(format: :pdf) %>
</div>
Add .no-print CSS class to elements that should not be printable:
/* app/assets/stylesheets/application.css */
@media print {
.no-print {
display: none !important;
}
}
/* other css classes you might want to add */
@media print {
body {
-webkit-print-color-adjust: exact;
background: #fff;
background-color: #fff;
float: none;
display: block;
}
.no_margin {
padding-left: 0px !important;
}
.no-print {
display: none !important;
}
.printer-preview-content,
.printer-preview-content_landscape {
max-width: 100% !important;
width: 100% !important;
height: auto !important;
padding: 0 !important;
margin: 0 !important;
}
.cover_div {
display: table;
}
}
Finally, use Ferrum to navigate to an internal or external URL and display it as PDF:
# app/controllers/home_controller.rb
class HomeController < ApplicationController
def index
respond_to do |format|
format.html
format.pdf do
handle_pdf_format
end
end
end
private
def handle_pdf_format
filename = controller_name
tmp = Tempfile.new("pdf-chrome-#{filename}")
browser = Ferrum::Browser.new
# browser.go_to("http://localhost:3000/home/index")
browser.go_to(home_index_url)
# browser.go_to("https://google.com")
# click_on_text "Accept all"
# browser.at_css(".QS5gu.sy4vM").click
sleep(0.3)
browser.pdf(
path: tmp.path,
format: "A4".to_sym,
landscape: false,
# margin: {top: 36, right: 36, bottom: 36, left: 36},
# preferCSSPageSize: true,
# printBackground: true
)
browser.quit
pdf_data = File.read(tmp.path)
pdf_filename = "#{filename}.pdf"
send_data(pdf_data,
filename: pdf_filename,
type: "application/pdf",
disposition: "inline")
ensure
tmp.close
tmp.unlink
end
end
It works well for publicly accessible URLs, however it is not so straightforwar for links that require current_user authentication. I’ve asked a question here https://github.com/rubycdp/ferrum/issues/423 and am hoping for an easy enough solution 🤠
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