Ruby on Rails 的 PDF 生成器 (从 HTML) 插件
Wicked PDF uses the shell utility wkhtmltopdf to serve a PDF file to a user from HTML. In other words, rather than dealing with a PDF generation DSL of some sort, you simply write an HTML view as you would normally, then let Wicked PDF take care of the hard stuff.
Wicked PDF has been verified to work on Ruby versions 2.2 through 3.2; Rails 4 through 7.0
Add this to your Gemfile and run bundle install:
gem 'wicked_pdf'
Then create the initializer with
rails generate wicked_pdf
You may also need to add
Mime::Type.register "application/pdf", :pdf
to config/initializers/mime_types.rb in older versions of Rails.
Because wicked_pdf is a wrapper for wkhtmltopdf, you'll need to install that, too.
The simplest way to install all of the binaries on most Linux or OSX systems is through the gem wkhtmltopdf-binary. Builds for other systems are available here To install that gem, add this:
gem 'wkhtmltopdf-binary'
To your Gemfile and run bundle install.
This gem currently installs version 0.12.x of wkhtmltopdf. Some of the options listed below are specific 0.9 or below, and others are for 0.12 and up.
You can see what flags are supported for the current version in wkhtmltopdf's auto-generated manual
If your wkhtmltopdf executable is not on your webserver's path, you can configure it in an initializer:
WickedPdf.configure do |c|
c.exe_path = '/usr/local/bin/wkhtmltopdf'
c.enable_local_file_access = true
end
For more information about wkhtmltopdf, see the project's homepage.
class ThingsController < ApplicationController
def show
respond_to do |format|
format.html
format.pdf do
render pdf: "file_name" # Excluding ".pdf" extension.
end
end
end
end
The wkhtmltopdf binary is run outside of your Rails application; therefore, your normal layouts will not work. If you plan to use any CSS, JavaScript, or image files, you must modify your layout so that you provide an absolute reference to these files. The best option for Rails without the asset pipeline is to use the wicked_pdf_stylesheet_link_tag, wicked_pdf_image_tag, and wicked_pdf_javascript_include_tag helpers or to go straight to a CDN (Content Delivery Network) for popular libraries such as jQuery.
<!doctype html>
<html>
<head>
<meta charset='utf-8' />
<%= wicked_pdf_stylesheet_link_tag "pdf" -%>
<%= wicked_pdf_javascript_include_tag "number_pages" %>
</head>
<body onload='number_pages'>
</body>
</html>
Using wicked_pdf_helpers with asset pipeline raises Asset names passed to helpers should not include the "/assets/" prefix. error. To work around this, you can use wicked_pdf_asset_base64 with the normal Rails helpers, but be aware that this will base64 encode your content and inline it in the page. This is very quick for small assets, but large ones can take a long time.
<!doctype html>
<html>
<head>
<meta charset='utf-8' />
<%= stylesheet_link_tag wicked_pdf_asset_base64("pdf") %>
<%= javascript_include_tag wicked_pdf_asset_base64("number_pages") %>
</head>
<body onload='number_pages'>
</body>
</html>
wicked_pdf supports webpack assets.
wicked_pdf_stylesheet_pack_tag for stylesheetswicked_pdf_javascript_pack_tag for javascriptswicked_pdf_asset_pack_path to access an asset directly, for example: image_tag wicked_pdf_asset_pack_path("media/images/foobar.png")It is best to precompile assets used in PDF views. This will help avoid issues when it comes to deploying, as Rails serves asset files differently between development and production (config.assets.compile = false), which can make it look like your PDFs work in development, but fail to load assets in production.
config.assets.precompile += ['blueprint/screen.css', 'pdf.css', 'jquery.ui.datepicker.js', 'pdf.js', ...etc...]
In this case, you can use that standard Rails helpers and point to the current CDN for whichever framework you are using. For jQuery, it would look somethng like this, given the current versions at the time of this writing.
<!doctype html>
<html>
<head>
<%= javascript_include_tag "http://code.jquery.com/jquery-1.10.0.min.js" %>
<%= javascript_include_tag "http://code.jquery.com/ui/1.10.3/jquery-ui.min.js" %>
NOTE: Certain options are only supported in specific versions of wkhtmltopdf.
…
By default, it will render without a layout (layout: false) and the template for the current controller and action.
Some of the options above are being passed to wkhtmltopdf binary. They can be used to control the options used in Webkit rendering before generating the PDF.
Examples of those options are:
print_media_type: true # Passes `--print-media-type`
no_background: true # Passes `--no-background`
You can see the complete list of options under "Global Options" in wkhtmltopdf usage docs.
If you need to just create a pdf and not display it:
…
If you need to display utf encoded characters, add this to your pdf views or layouts:
<meta charset="utf-8" />
If you need to return a PDF in a controller with Rails in API mode:
pdf_html = ActionController::Base.new.render_to_string(template: 'controller_name/action_name', layout: 'pdf')
pdf = WickedPdf.new.pdf_from_string(pdf_html)
send_data pdf, filename: 'file.pdf'
You can control page breaks with CSS.
Add a few styles like this to your stylesheet or page:
div.alwaysbreak { page-break-before: always; }
div.nobreak:before { clear:both; }
div.nobreak { page-break-inside: avoid; }
A bit of javascript can help you number your pages. Create a template or header/footer file with this:
…
Anything with a class listed in "var x" above will be auto-filled at render time.
If you do not have explicit page breaks (and therefore do not have any "page" class), you can also use wkhtmltopdf's built in page number generation by setting one of the headers to "[page]":
render pdf: 'filename', header: { right: '[page] of [topage]' }
You can put your default configuration, applied to all pdf's at "wicked_pdf.rb" initializer.
If you would like to have WickedPdf automatically generate PDF views for all (or nearly all) pages by appending .pdf to the URL, add the following to your Rails app:
# in application.rb (Rails3) or environment.rb (Rails2)
require 'wicked_pdf'
config.middleware.use WickedPdf::Middleware
If you want to turn on or off the middleware for certain URLs, use the :only or :except conditions like so:
# conditions can be plain strings or regular expressions, and you can supply only one or an array
config.middleware.use WickedPdf::Middleware, {}, only: '/invoice'
config.middleware.use WickedPdf::Middleware, {}, except: [ %r[^/admin], '/secret', %r[^/people/\d] ]
If you use the standard render pdf: 'some_pdf' in your app, you will want to exclude those actions from the middleware.
To include a rendered pdf file in an email you can do the following:
attachments['attachment.pdf'] = WickedPdf.new.pdf_from_string(
render_to_string('link_to_view.pdf.erb', layout: 'pdf')
)
This will render the pdf to a string and include it in the email. This is very slow so make sure you schedule your email delivery in a job.
Mike Ackerman's post How To Create PDFs in Rails
Andreas Happe's post Generating PDFs from Ruby on Rails
JESii's post WickedPDF, wkhtmltopdf, and Heroku...a tricky combination
Berislav Babic's post Send PDF attachments from Rails with WickedPdf and ActionMailer
Corsego's 2021 post Complete guide to generating PDFs with gem wicked_pdf
PDFTron's post How to Generate PDFs With Ruby on Rails
StackOverflow questions with the tag "wicked-pdf"
Now you can use a debug param on the URL that shows you the content of the pdf in plain html to design it faster.
First of all you must configure the render parameter show_as_html: params.key?('debug') and then just use it like you normally would but add "debug" as a GET param in the URL:
http://localhost:3001/CONTROLLER/X.pdf?debug
However, the wicked_pdf_* helpers will use file:/// paths for assets when using :show_as_html, and your browser's cross-domain safety feature will kick in, and not render them. To get around this, you can load your assets like so in your templates:
<%= params.key?('debug') ? image_tag('foo') : wicked_pdf_image_tag('foo') %>
If one image from your HTML cannot be found (relative or wrong path for example), others images with right paths may not be displayed in the output PDF as well (it seems to be an issue with wkhtmltopdf).
wkhtmltopdf may render at different resolutions on different platforms. For example, Linux prints at 75 dpi (native for WebKit) while on Windows it's at the desktop's DPI (which is normally 96 dpi). Use :zoom => 0.78125 (75/96) to match Linux rendering to Windows.
WickedPdf renders page content on the server by saving HTML and assets to temporary files on disk, then executing wkhtmltopdf to convert that HTML to a PDF file.
It is highly recommended if you allow user-generated HTML/CSS/JS to be converted to PDF, you sanitize it first, or at least disallow requesting content from internal IP addresses and hostnames.
For example, these could potentially leak internal AWS metadata:
<iframe src="http://169.254.169.254/latest/meta-data/"></iframe>
<object data="http://169.254.169.254/latest/meta-data/" type="text/html">
Thank you to Adam Gold from Snyk for reporting this. We are considering adding host allow & block lists and/or potentially HTML element sanitizing. Please open an issue or PR to help us out with this.
You may have noticed: this plugin is heavily inspired by the PrinceXML plugin princely. PrinceXML's cost was prohibitive for me. So, with a little help from some friends (thanks jqr), I tracked down wkhtmltopdf, and here we are.
git checkout -b my-new-feature)rake)git commit -am 'Add some feature')Long term plans given the deprecation of wkhtmltopdf?
Gem breaks with Shakapacker version 10.0
PDF Rendering Fail on Heroku-24 Stack
ActionView::Template::Error uninitialized constant WickedPdf::WickedPdfHelper::Assets::SprocketsEnvironment::Sprockets