Nokogiri adds a lot of weight to ActionView

Rails goes out of its way to avoid forcing an installation of bcrypt because it is a binary library. See

Nokogiri forces installation of 2 binary libraries (libxml2 and libxslt), so one would expect it not to be a dependency of any of the core components of Rails.

However, starting with actionview 4.2.0, nokogiri is now a dependency.

That means every time actionview appears in a Gemfile.lock, so does nokogiri. I would often include ActionView 4.1 in non-Rails projects just to use number_to_currency, but now with the nokogiri dependency, the overhead is hardly worth it.

Consider the fact that I’m deploying about 5 such projects to the same server, all using separate BUNDLE_PATH’s. That means 5 installations of nokogiri, none of which are being used. This adds time to every capistrano bundler:install and a significant amount of disk space is wasted on this. For any other gem, this wouldn’t make much of a difference, but nokogiri is really big and takes a long time to install, and Rails has already set a precedent by not including the (much lighter) bcrypt.

Is the rails-core team open to the following solutions:

Um, deviating a little from your particular concern (which may or may not be justified), but you really can’t complain about being forced to include a gem multiple times when you’re including action view (and thus active support, I18n, TZInfo, builder, erubis, and a couple more…) just to use a method that you could very well implement yourself in very simple ruby.

I mean, you were pulling like 8 or 9 gems (without counting nokogiri) just so you can avoid formatting a number a little bit, rounding it off, and prepending a “$” (or your currency of choice) to a string.

…but then you complain that now you have to install an extra gem?




It’s not that they have to install an extra gem that’s the problem, I think. The problem is that Nokogiri is only used by a tiny, tiny subset of ActionView and during the course of the application that tiny subset might not be used at all.

The installation of Nokogiri can cause issues for people who are new to Rails if they’re missing the libxml or libxslt libraries. A solution is that they install those libraries. Another is that we remove the Nokogiri dependency.

I’m +1 on separating it out so that it’s an optional part of ActionView, if that’s at all possible.

As a side note, the base functionality of the number helpers was moved to Active Support, so you don’t need to rely on Action View anymore in this scenario.

(I understand the concern about including nokogiri, just wanted to make sure that everyone was aware of this).

Thank you for the feedback. Thank you especially to Carlos for pointing out that I could just include ActiveSupport without ActionView.

I could have left out the personal anecdote–Ryan makes a good point that the real issue is that nokogiri should not be a dependency when it is needed by only a small subset of functionality, that often is not used at all.

So, rails-core team, are you guys on board?

Nokogiri is needed for tests and I don’t think tests are often used, at least they should. I still don’t see any reason for doing this even more because almost all Rails applications use capybara and nokogiri is also a capybara dependency.

  1. By the same logic, almost all Rails applications use devise, and bcrypt is a dependency of devise.

  2. capybara is not typically a dependency in production

  1. rails-api ( is merged into master (though not into 4.2-stable). “ApplicationController < ActionController::API” would would be a very reasonable use case for having no need for capybara. As this is going to part of Rails in the next major release, it seems that Rails applications that only respond_to JSON will become more common. While it’s still possible to use capybara for such applications, there are much more lightweight options (such as Webrick + Net::HTTP, which I often use instead of capybara for lightweight sinatra apps). So even if currently most Rails apps use capybara, a growing number of them won’t with the next release.


I made 3 strong arguments in response to your point about capybara. I would have appreciated a response explaining if any of my reasoning is wrong here.

This is not a difficult PR and I still feel the case for it is strong but I don’t want to start working on it while I’m waiting to hear from you.

I think it is worth to experiment yes, I don’t want to decline anything without seeing the code and how it would feel. I can see advantages of doing that.

Thank you.

I will aim for submitting a PR over the coming weekend.