generating pdf hangs on rails 4 using PDFkit gem

问题

I'm able to download pdf file with:

curl google.com | wkhtmltopdf - test.pdf

so it means, wkhtmlpdf installation was successful.

But, when I try to generate pdf file by accessing http://localhost:3000/contacts/1.pdf it hangs. In the status bar it shows: Waiting for localhost...

Rails server output:

Started GET "/contacts/1.pdf" for 127.0.0.1 at 2013-07-28 21:45:06 +0900
  ActiveRecord::SchemaMigration Load (0.1ms)  SELECT "schema_migrations".* FROM "schema_migrations"
Processing by ContactsController#show as HTML
  Parameters: {"id"=>"1"}
  Contact Load (0.3ms)  SELECT "contacts".* FROM "contacts" WHERE "contacts"."id" = ? LIMIT 1  [["id", "1"]]
  Rendered contacts/show.html.erb within layouts/application (1.4ms)
Completed 200 OK in 99ms (Views: 57.0ms | ActiveRecord: 0.7ms)

Gemfile:

gem 'pdfkit'

application.rb:

config.middleware.use "PDFKit::Middleware"

According to the PDFKit railscast this should be enough for generating pdf files just by adding .pdf ...

UPDATE:

show.html.erb:

<p id="notice"><%= notice %></p>

<p>
  <strong>Name:</strong>
  <%= @contact.name %>
</p>

<p>
  <strong>Age:</strong>
  <%= @contact.age %>
</p>

<%= link_to 'Edit', edit_contact_path(@contact) %> |
<%= link_to 'Back', contacts_path %>

layouts/application.html.erb:

<!DOCTYPE html>
<html>
<head>
  <title>Pdftest</title>
  <%= stylesheet_link_tag    "application", media: "all", "data-turbolinks-track" => true %>
  <%= javascript_include_tag "application", "data-turbolinks-track" => true %>
  <%= csrf_meta_tags %>
</head>
<body>

<%= yield %>

</body>
</html>

UPDATE 2:

Thanks to @Arman H for helping me to figure out that I have to specify absolute path for assets instead of a relative ones. When I removed the following lines I was able to generate PDF file:

<%= stylesheet_link_tag    "application", media: "all", "data-turbolinks-track" => true %>
<%= javascript_include_tag "application", "data-turbolinks-track" => true %>

Now, I can't get how to substitute this with an absolute paths. It seems this post is what I need, but I still can't figure out how this would look like for my case.

回答1:

The issue was due to stylesheet_link_tag and javascript_include_tag using relative URLs, which often causes wkhtmltopdf to hang when loading assets from the same server that wkhtmltopdf is running on.

Using absolute URLs for assets solved the problem.

Set asset_host in Rails' config, which also affects stylesheet_link_tag and javascript_include_tag:

# Modify asset host config setting in `config/application.rb`
# Or create a new initializer: `config/initializers/wkhtmltopdf.rb`
config.action_controller.asset_host = "http://mysite.com"

# Or you can have different hosts for development (local) and production (CDN):
# In `config/environments/development.rb`
config.action_controller.asset_host = "http://localhost"
# In `config/environments/production.rb`
config.action_controller.asset_host = "http://d111111abcdef8.cloudfront.net"

回答2:

Setting config.action_controller.asset_host = "http://localhost" in development.rb actually didn't work for me. That is, the PDF generation would work, but then assets wouldn't come through when rendering HTML.

I followed the method here: http://jguimont.com/post/2627758108/pdfkit-and-its-middleware-on-heroku

and it worked like a charm for me. Hope this helps someone. Just throw assets.rb in config/intializers and you're good to go.

回答3:

I had the same issue in which my log showed the page had rendered however no pdf was generated and the browser would hang. It ended up having nothing to do with OS compatability, missing librariers, gems nor dependencies but instead I needed to raise the max allowable thread count for my Puma server (which had been set to 1) upto 2 or more. This then generated pdf's as normal.

来源：https://stackoverflow.com/questions/17908359/generating-pdf-hangs-on-rails-4-using-pdfkit-gem

标签

ruby-on-rails

pdf

pdf-generation

ruby-on-rails-4

wkhtmltopdf