Introduce `render :plain` for render plain text

This is as an option to render content with a content type of
`text/plain`. This is the preferred option if you are planning to render
a plain text content.

Please see #12374 for more detail.

3 files changed, 6 insertions, 2 deletions

diff --git a/actionview/lib/action_view/helpers/rendering_helper.rb b/actionview/lib/action_view/helpers/rendering_helper.rb
index 77d63b7f86..4eae80cd93 100644
--- a/actionview/lib/action_view/helpers/rendering_helper.rb
+++ b/actionview/lib/action_view/helpers/rendering_helper.rb
@@ -12,6 +12,8 @@ module ActionView
       # * <tt>:file</tt> - Renders an explicit template file (this used to be the old default), add :locals to pass in those.
       # * <tt>:inline</tt> - Renders an inline template similar to how it's done in the controller.
       # * <tt>:text</tt> - Renders the text passed in out.
+      # * <tt>:plain</tt> - Renders the text passed in out. Setting the content
+      # type as <tt>text/plain</tt>.
       # * <tt>:body</tt> - Renders the text passed in, and does not set content
       # type in the response.
       #
diff --git a/actionview/lib/action_view/layouts.rb b/actionview/lib/action_view/layouts.rb
index b67b749af5..3f049e838a 100644
--- a/actionview/lib/action_view/layouts.rb
+++ b/actionview/lib/action_view/layouts.rb
@@ -420,7 +420,7 @@ module ActionView
     end
 
     def _include_layout?(options)
-      (options.keys & [:body, :text, :inline, :partial]).empty? || options.key?(:layout)
+      (options.keys & [:body, :text, :plain, :inline, :partial]).empty? || options.key?(:layout)
     end
   end
 end
diff --git a/actionview/lib/action_view/renderer/template_renderer.rb b/actionview/lib/action_view/renderer/template_renderer.rb
index 8f24f8dab0..ba946b230a 100644
--- a/actionview/lib/action_view/renderer/template_renderer.rb
+++ b/actionview/lib/action_view/renderer/template_renderer.rb
@@ -25,6 +25,8 @@ module ActionView
         Template::Text.new(options[:body])
       elsif options.key?(:text)
         Template::Text.new(options[:text], formats.first)
+      elsif options.key?(:plain)
+        Template::Text.new(options[:plain])
       elsif options.key?(:file)
         with_fallbacks { find_template(options[:file], nil, false, keys, @details) }
       elsif options.key?(:inline)
@@ -37,7 +39,7 @@ module ActionView
           find_template(options[:template], options[:prefixes], false, keys, @details)
         end
       else
-        raise ArgumentError, "You invoked render but did not give any of :partial, :template, :inline, :file, :text or :body option."
+        raise ArgumentError, "You invoked render but did not give any of :partial, :template, :inline, :file, :plain, :text or :body option."
       end
     end