Use `Mime[:foo]` instead of `Mime::Type[:FOO]` for back compat

Rails 4.x and earlier didn't support `Mime::Type[:FOO]`, so libraries
that support multiple Rails versions would've had to feature-detect
whether to use `Mime::Type[:FOO]` or `Mime::FOO`.

`Mime[:foo]` has been around for ages to look up registered MIME types
by symbol / extension, though, so libraries and plugins can safely
switch to that without breaking backward- or forward-compatibility.

Note: `Mime::ALL` isn't a real MIME type and isn't registered for lookup
by type or extension, so it's not available as `Mime[:all]`. We use it
internally as a wildcard for `respond_to` negotiation. If you use this
internal constant, continue to reference it with `Mime::ALL`.

Ref. efc6dd550ee49e7e443f9d72785caa0f240def53

1 files changed, 1 insertions, 1 deletions

diff --git a/actionpack/lib/action_controller/metal/rendering.rb b/actionpack/lib/action_controller/metal/rendering.rb
index 1ecccf9864..172fbdf954 100644
--- a/actionpack/lib/action_controller/metal/rendering.rb
+++ b/actionpack/lib/action_controller/metal/rendering.rb
@@ -64,7 +64,7 @@ module ActionController
     end
 
     def _set_html_content_type
-      self.content_type = Mime::Type[:HTML].to_s
+      self.content_type = Mime[:html].to_s
     end
 
     def _set_rendered_content_type(format)