Allow using components with view_component

While Rails provides a lot of functionality by default, there's one
missing piece which is present in frameworks like Django or Phoenix: the
so-called "view models", or "components".

It isn't easy to extract methods in a standard Rails view/partial, since
extracting them to a helper will make them available to all views, and
so two helper methods can't have the same name. It's also hard to
organize the code in modules, and due to that it's hard to figure out
where a certain helper method is supposed to be called from.
Furthermore, object-oriented techniques like inheritance can't be
applied, and so in CONSUL customizing views is harder that customizing
models.

Components fix all these issues, and work the way Ruby objects usually
do.

Components are also a pattern whose popularity has increased a lot in
the last few years, with JavaScript frameworks like React using them
heavily. While React's components aren't exactly the same as the
components we're going to use, the concept is really similar.

I've always liked the idea of components. However, there wasn't a stable
gem we could safely use. The most popular gem (cells) hasn't been
maintained for years, and we have to be very careful choosing which gems
CONSUL should depend on.

The view_component gem is maintained by GitHub, which is as a guarantee
of future maintenance as it can be (not counting the Rails core team),
and its usage started growing after RailsConf 2019. While that's
certainly not a huge amount of time, it's not that we're using an
experimental gem either.

There's currently a conflict between view_component and wicked_pdf.
We're adding a monkey-patch with the fix until it's merged in
wicked_pdf.

Gemfile

@@ -59,6 +59,7 @@ gem "translator-text", "~> 0.1.0"
 gem "turbolinks", "~> 5.2.1"
 gem "turnout", "~> 2.5.0"
 gem "uglifier", "~> 4.2.0"
+gem "view_component", "~> 2.19.1", require: "view_component/engine"
 gem "whenever", "~> 1.0.0", require: false
 gem "wicked_pdf", "~> 2.1.0"
 gem "wkhtmltopdf-binary", "~> 0.12.4"

Gemfile.lock

@@ -608,6 +608,8 @@ GEM
     uniform_notifier (1.13.0)
     user_agent_parser (2.6.0)
     uuidtools (2.1.5)
+    view_component (2.19.1)
+      activesupport (>= 5.0.0, < 7.0)
     warden (1.2.9)
       rack (>= 2.0.9)
     wasabi (3.5.0)
@@ -728,6 +730,7 @@ DEPENDENCIES
   turbolinks (~> 5.2.1)
   turnout (~> 2.5.0)
   uglifier (~> 4.2.0)
+  view_component (~> 2.19.1)
   web-console (~> 3.7.0)
   webdrivers (~> 4.4.1)
   whenever (~> 1.0.0)

app/components/application_component.rb

@@ -0,0 +1,2 @@
+class ApplicationComponent < ViewComponent::Base
+end

config/application.rb

@@ -112,6 +112,7 @@ module Consul
     # * English: https://github.com/consul/consul/blob/master/CUSTOMIZE_EN.md
     # * Spanish: https://github.com/consul/consul/blob/master/CUSTOMIZE_ES.md
     #
+    config.autoload_paths << "#{Rails.root}/app/components/custom"
     config.autoload_paths << "#{Rails.root}/app/controllers/custom"
     config.autoload_paths << "#{Rails.root}/app/models/custom"
     config.paths["app/views"].unshift(Rails.root.join("app", "views", "custom"))

config/initializers/wicked_pdf.rb

@@ -1,3 +1,27 @@
+class WickedPdf
+  # Wicked Pdf magic breaks ViewComponent
+  # https://github.com/mileszs/wicked_pdf/pull/925
+  module PdfHelper
+    def render(*args)
+      options = args.first
+      if options.is_a?(Hash) && options.key?(:pdf)
+        render_with_wicked_pdf(options)
+      else
+        super
+      end
+    end
+
+    def render_to_string(*args)
+      options = args.first
+      if options.is_a?(Hash) && options.key?(:pdf)
+        render_to_string_with_wicked_pdf(options)
+      else
+        super
+      end
+    end
+  end
+end
+
 # WickedPDF Global Configuration
 #
 # Use this to set up shared configuration options for your entire application.

spec/rails_helper.rb

@@ -11,6 +11,11 @@ require "spec_helper"
 require "capybara/rails"
 require "capybara/rspec"
 require "selenium/webdriver"
+require "view_component/test_helpers"
+
+RSpec.configure do |config|
+  config.include ViewComponent::TestHelpers, type: :component
+end
 
 Rails.application.load_tasks if Rake::Task.tasks.empty?