Change `ActionDispatch::Response#content_type` returning Content-Type header as it is

Since #35709, `Response#conten_type` returns only MIME type correctly.
It is a documented behavior that this method only returns MIME type, so
this change seems appropriate.
https://github.com/rails/rails/blob/39de7fac0507070e3c5f8b33fbad6fced84d97ed/actionpack/lib/action_dispatch/http/response.rb#L245-L249

But unfortunately, some users expect this method to return all
Content-Type that does not contain charset. This seems to be breaking
changes.

We can change this behavior with the deprecate cycle.
But, in that case, a method needs that include Content-Type with
additional parameters. And that method name is probably the
`content_type` seems to properly.

So I changed the new behavior to more appropriate `media_type` method.
And `Response#content_type` changed (as the method name) to return Content-Type
header as it is.

Fixes #35709.

[Rafael Mendonça França & Yuuji Yaginuma ]

4 files changed, 4 insertions, 4 deletions

diff --git a/actionpack/lib/action_controller/metal.rb b/actionpack/lib/action_controller/metal.rb
index b9088e6d86..9ca0bbb9db 100644
--- a/actionpack/lib/action_controller/metal.rb
+++ b/actionpack/lib/action_controller/metal.rb
@@ -148,7 +148,7 @@ module ActionController
     attr_internal :response, :request
     delegate :session, to: "@_request"
     delegate :headers, :status=, :location=, :content_type=,
-             :status, :location, :content_type, to: "@_response"
+             :status, :location, :content_type, :media_type, to: "@_response"
 
     def initialize
       @_request = nil
diff --git a/actionpack/lib/action_controller/metal/mime_responds.rb b/actionpack/lib/action_controller/metal/mime_responds.rb
index bf5e7a433f..5c6f7fe396 100644
--- a/actionpack/lib/action_controller/metal/mime_responds.rb
+++ b/actionpack/lib/action_controller/metal/mime_responds.rb
@@ -205,7 +205,7 @@ module ActionController #:nodoc:
       yield collector if block_given?
 
       if format = collector.negotiate_format(request)
-        if content_type && content_type != format
+        if media_type && media_type != format
           raise ActionController::RespondToMismatchError
         end
         _process_format(format)
diff --git a/actionpack/lib/action_controller/metal/renderers.rb b/actionpack/lib/action_controller/metal/renderers.rb
index b81d3ef539..a251c29d23 100644
--- a/actionpack/lib/action_controller/metal/renderers.rb
+++ b/actionpack/lib/action_controller/metal/renderers.rb
@@ -157,7 +157,7 @@ module ActionController
       json = json.to_json(options) unless json.kind_of?(String)
 
       if options[:callback].present?
-        if content_type.nil? || content_type == Mime[:json]
+        if media_type.nil? || media_type == Mime[:json]
           self.content_type = Mime[:js]
         end
 
diff --git a/actionpack/lib/action_controller/metal/rendering.rb b/actionpack/lib/action_controller/metal/rendering.rb
index 7d0a944381..7f7c736965 100644
--- a/actionpack/lib/action_controller/metal/rendering.rb
+++ b/actionpack/lib/action_controller/metal/rendering.rb
@@ -73,7 +73,7 @@ module ActionController
       end
 
       def _set_rendered_content_type(format)
-        if format && !response.content_type
+        if format && !response.media_type
           self.content_type = format.to_s
         end
       end