Disentangle Action Text from ApplicationController

This commit allows Action Text to be used without having an
ApplicationController defined.  In doing so, it also fixes Action Text
attachments to render the correct URL host in mailers.

It also avoids allocating an ActionController::Renderer per request.

Fixes #37183.
Fixes #35578.
Fixes #36963.
Closes #38714.

Co-authored-by: Jeremy Daer <jeremydaer@gmail.com>

actionpack/lib/action_controller/renderer.rb

@@ -99,6 +99,7 @@ module ActionController
       instance.set_response! controller.make_response!(request)
       instance.render_to_string(*args)
     end
+    alias_method :render_to_string, :render # :nodoc:
 
     private
       def normalize_keys(defaults, env)

actiontext/app/helpers/action_text/content_helper.rb

@@ -10,6 +10,7 @@ module ActionText
     mattr_accessor(:scrubber)
 
     def render_action_text_content(content)
+      self.prefix_partial_path_with_controller_namespace = false
       sanitize_action_text_content(render_action_text_attachments(content))
     end
 

actiontext/lib/action_text.rb

@@ -16,6 +16,7 @@ module ActionText
   autoload :Fragment
   autoload :HtmlConversion
   autoload :PlainTextConversion
+  autoload :Rendering
   autoload :Serialization
   autoload :TrixAttachment
 

actiontext/lib/action_text/attachments/trix_conversion.rb

@@ -28,7 +28,7 @@ module ActionText
       private
         def trix_attachment_content
           if partial_path = attachable.try(:to_trix_content_attachment_partial_path)
-            ActionText::Content.renderer.render(partial: partial_path, object: self, as: model_name.element)
+            ActionText::Content.render(partial: partial_path, object: self, as: model_name.element)
           end
         end
     end

actiontext/lib/action_text/content.rb

@@ -1,12 +1,8 @@
 # frozen_string_literal: true
 
-require "active_support/core_ext/module/attribute_accessors_per_thread"
-
 module ActionText
   class Content
-    include Serialization
-
-    thread_cattr_accessor :renderer
+    include Rendering, Serialization
 
     attr_reader :fragment
 
@@ -88,7 +84,7 @@ module ActionText
     end
 
     def to_rendered_html_with_layout
-      renderer.render(partial: "action_text/content/layout", locals: { content: self })
+      render partial: "action_text/content/layout", locals: { content: self }
     end
 
     def to_s

actiontext/lib/action_text/engine.rb

@@ -37,21 +37,24 @@ module ActionText
     end
 
     initializer "action_text.helper" do
-      ActiveSupport.on_load(:action_controller_base) do
-        helper ActionText::Engine.helpers
+      %i[action_controller_base action_mailer].each do |abstract_controller|
+        ActiveSupport.on_load(abstract_controller) do
+          helper ActionText::Engine.helpers
+        end
       end
     end
 
-    initializer "action_text.renderer" do |app|
-      app.executor.to_run      { ActionText::Content.renderer = ApplicationController.renderer }
-      app.executor.to_complete { ActionText::Content.renderer = ApplicationController.renderer }
-
+    initializer "action_text.renderer" do
       ActiveSupport.on_load(:action_text_content) do
-        self.renderer = ApplicationController.renderer
+        self.renderer = Class.new(ActionController::Base).renderer
       end
 
-      ActiveSupport.on_load(:action_controller_base) do
-        before_action { ActionText::Content.renderer = ApplicationController.renderer.new(request.env) }
+      %i[action_controller_base action_mailer].each do |abstract_controller|
+        ActiveSupport.on_load(abstract_controller) do
+          around_action do |controller, action|
+            ActionText::Content.with_renderer(controller, &action)
+          end
+        end
       end
     end
 

actiontext/lib/action_text/rendering.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+require "active_support/concern"
+require "active_support/core_ext/module/attribute_accessors_per_thread"
+
+module ActionText
+  module Rendering #:nodoc:
+    extend ActiveSupport::Concern
+
+    included do
+      thread_cattr_accessor :renderer, instance_accessor: false
+      delegate :render, to: :class
+    end
+
+    class_methods do
+      def with_renderer(renderer)
+        previous_renderer = self.renderer
+        self.renderer = renderer
+        yield
+      ensure
+        self.renderer = previous_renderer
+      end
+
+      def render(*args, &block)
+        renderer.render_to_string(*args, &block)
+      end
+    end
+  end
+end

actiontext/test/dummy/app/controllers/admin/messages_controller.rb

@@ -0,0 +1,5 @@
+class Admin::MessagesController < ActionController::Base
+  def show
+    @message = Message.find(params[:id])
+  end
+end

actiontext/test/dummy/app/controllers/application_controller.rb

@@ -1,2 +0,0 @@
-class ApplicationController < ActionController::Base
-end

actiontext/test/dummy/app/controllers/messages_controller.rb

@@ -1,4 +1,4 @@
-class MessagesController < ApplicationController
+class MessagesController < ActionController::Base
   before_action :set_message, only: [:show, :edit, :update, :destroy]
 
   # GET /messages

actiontext/test/dummy/app/mailers/messages_mailer.rb

@@ -0,0 +1,6 @@
+class MessagesMailer < ApplicationMailer
+  def notification
+    @message = params[:message]
+    mail to: params[:recipient], subject: "NEW MESSAGE: #{@message.subject}"
+  end
+end

actiontext/test/dummy/app/views/admin/messages/show.html.erb

@@ -0,0 +1,16 @@
+<dl>
+  <dt>Subject</dt>
+  <dd>
+    <span id="subject"><%= @message.subject %></span>
+  </dd>
+
+  <dt>Content (Plain Text)</dt>
+  <dd>
+    <pre id="content-plain"><%= @message.content.to_plain_text %></pre>
+  </dd>
+
+  <dt>Content (HTML)</dt>
+  <dd>
+    <div id="content-html"><%= @message.content %></div>
+  </dd>
+</dl>

actiontext/test/dummy/app/views/layouts/application.html.erb

@@ -3,9 +3,6 @@
   <head>
     <title>Dummy</title>
     <%= csrf_meta_tags %>
-
-    <%= stylesheet_link_tag 'application', media: 'all' %>
-    <%= javascript_pack_tag 'application' %>
   </head>
 
   <body>

actiontext/test/dummy/app/views/messages/show.html.erb

@@ -1,13 +1,8 @@
 <p id="notice"><%= notice %></p>
 
-<p>
-  <strong>Subject:</strong>
-  <%= @message.subject %>
-</p>
+<h1 id="subject"><%= @message.subject %></h1>
 
-<div class="trix-content">
-  <%= @message.content.html_safe %>
-</div>
+<div id="content"><%= @message.content %></div>
 
 <%= link_to 'Edit', edit_message_path(@message) %> |
 <%= link_to 'Back', messages_path %>

actiontext/test/dummy/app/views/messages_mailer/notification.html.erb

@@ -0,0 +1 @@
+<div id="message-content"><%= @message.content %></div>

actiontext/test/dummy/config/routes.rb

@@ -1,4 +1,7 @@
 Rails.application.routes.draw do
   resources :messages
-  # For details on the DSL available within this file, see https://guides.rubyonrails.org/routing.html
+
+  namespace :admin do
+    resources :messages, only: [:show]
+  end
 end

actiontext/test/integration/controller_render_test.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class ActionText::ControllerRenderTest < ActionDispatch::IntegrationTest
+  test "uses current request environment" do
+    blob = create_file_blob(filename: "racecar.jpg", content_type: "image/jpg")
+    message = Message.create!(content: ActionText::Content.new.append_attachables(blob))
+
+    host! "loocalhoost"
+    get message_path(message)
+    assert_select "#content img" do |imgs|
+      imgs.each { |img| assert_match %r"//loocalhoost/", img["src"] }
+    end
+  end
+
+  test "resolves partials when controller is namespaced" do
+    blob = create_file_blob(filename: "racecar.jpg", content_type: "image/jpg")
+    message = Message.create!(content: ActionText::Content.new.append_attachables(blob))
+
+    get admin_message_path(message)
+    assert_select "#content-html .trix-content .attachment--jpg"
+  end
+end

actiontext/test/integration/mailer_render_test.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class ActionText::MailerRenderTest < ActionMailer::TestCase
+  test "uses default_url_options" do
+    original_default_url_options = ActionMailer::Base.default_url_options
+    ActionMailer::Base.default_url_options = { host: "hoost" }
+
+    blob = create_file_blob(filename: "racecar.jpg", content_type: "image/jpg")
+    message = Message.new(content: ActionText::Content.new.append_attachables(blob))
+
+    MessagesMailer.with(recipient: "test", message: message).notification.deliver_now
+
+    assert_select_email do
+      assert_select "#message-content img" do |imgs|
+        imgs.each { |img| assert_match %r"//hoost/", img["src"] }
+      end
+    end
+  ensure
+    ActionMailer::Base.default_url_options = original_default_url_options
+  end
+end

actiontext/test/unit/content_test.rb

@@ -107,6 +107,15 @@ class ActionText::ContentTest < ActiveSupport::TestCase
     assert_equal "<blockquote><div>#{attachment_html}</div></blockquote>", content_from_html(html).to_html
   end
 
+  test "renders with layout when ApplicationController is not defined" do
+    html = "<h1>Hello world</h1>"
+    rendered = content_from_html(html).to_rendered_html_with_layout
+
+    assert_includes rendered, html
+    assert_match %r/\A#{Regexp.escape '<div class="trix-content">'}/, rendered
+    assert_not defined?(::ApplicationController)
+  end
+
   private
     def content_from_html(html)
       ActionText::Content.new(html).tap do |content|

actionview/lib/action_view/base.rb

@@ -151,7 +151,7 @@ module ActionView #:nodoc:
     # Specify whether rendering within namespaced controllers should prefix
     # the partial paths for ActiveModel objects with the namespace.
     # (e.g., an Admin::PostsController would render @post using /admin/posts/_post.erb)
-    cattr_accessor :prefix_partial_path_with_controller_namespace, default: true
+    class_attribute :prefix_partial_path_with_controller_namespace, default: true
 
     # Specify default_formats that can be rendered.
     cattr_accessor :default_formats