2 files changed, 9 insertions, 5 deletions
diff --git a/actionpack/lib/action_dispatch/http/mime_types.rb b/actionpack/lib/action_dispatch/http/mime_types.rb
index 0e4da36038..01a10c693b 100644
--- a/actionpack/lib/action_dispatch/http/mime_types.rb
+++ b/actionpack/lib/action_dispatch/http/mime_types.rb
@@ -27,7 +27,7 @@ Mime::Type.register "application/x-www-form-urlencoded", :url_encoded_form
 
 # http://www.ietf.org/rfc/rfc4627.txt
 # http://www.json.org/JSONRequest.html
-Mime::Type.register "application/json", :json, %w( text/x-json application/jsonrequest )
+Mime::Type.register "application/json", :json, %w( text/x-json application/jsonrequest application/vnd.api+json )
 
 Mime::Type.register "application/pdf", :pdf, [], %w(pdf)
 Mime::Type.register "application/zip", :zip, [], %w(zip)
diff --git a/actionpack/lib/action_dispatch/http/request.rb b/actionpack/lib/action_dispatch/http/request.rb
index a10bc3e419..f3de19db0b 100644
--- a/actionpack/lib/action_dispatch/http/request.rb
+++ b/actionpack/lib/action_dispatch/http/request.rb
@@ -181,7 +181,7 @@ module ActionDispatch
     #
     #   request.headers["Content-Type"] # => "text/plain"
     def headers
-      Http::Headers.new(@env)
+      @headers ||= Http::Headers.new(@env)
     end
 
     # Returns a +String+ with the last requested path including their params.
@@ -235,11 +235,13 @@ module ActionDispatch
     end
     alias :xhr? :xml_http_request?
 
+    # Returns the IP address of client as a +String+.
     def ip
       @ip ||= super
     end
 
-    # Originating IP address, usually set by the RemoteIp middleware.
+    # Returns the IP address of client as a +String+,
+    # usually set by the RemoteIp middleware.
     def remote_ip
       @remote_ip ||= (@env["action_dispatch.remote_ip"] || ip).to_s
     end
@@ -256,13 +258,13 @@ module ActionDispatch
       env[ACTION_DISPATCH_REQUEST_ID]
     end
 
-    def request_id=(id)
+    def request_id=(id) # :nodoc:
       env[ACTION_DISPATCH_REQUEST_ID] = id
     end
 
     alias_method :uuid, :request_id
 
-    def x_request_id
+    def x_request_id # :nodoc
       @env[HTTP_X_REQUEST_ID]
     end
 
@@ -293,6 +295,8 @@ module ActionDispatch
       end
     end
 
+    # returns true if request content mime type is
+    # +application/x-www-form-urlencoded+ or +multipart/form-data+.
     def form_data?
       FORM_DATA_MEDIA_TYPES.include?(content_mime_type.to_s)
     end