1 files changed, 28 insertions, 21 deletions

diff --git a/actionpack/lib/action_dispatch/http/response.rb b/actionpack/lib/action_dispatch/http/response.rb
index 1515d59df3..e8173e2a99 100644
--- a/actionpack/lib/action_dispatch/http/response.rb
+++ b/actionpack/lib/action_dispatch/http/response.rb
@@ -1,7 +1,7 @@
-require 'active_support/core_ext/module/attribute_accessors'
-require 'action_dispatch/http/filter_redirect'
-require 'action_dispatch/http/cache'
-require 'monitor'
+require "active_support/core_ext/module/attribute_accessors"
+require "action_dispatch/http/filter_redirect"
+require "action_dispatch/http/cache"
+require "monitor"
 
 module ActionDispatch # :nodoc:
   # Represents an HTTP response generated by a controller action. Use it to
@@ -41,7 +41,7 @@ module ActionDispatch # :nodoc:
 
       def []=(k,v)
         if @response.sending? || @response.sent?
-          raise ActionDispatch::IllegalStateError, 'header already sent'
+          raise ActionDispatch::IllegalStateError, "header already sent"
         end
 
         super
@@ -67,7 +67,7 @@ module ActionDispatch # :nodoc:
 
     alias_method :headers,  :header
 
-    delegate :[], :[]=, :to => :@header
+    delegate :[], :[]=, to: :@header
 
     def each(&block)
       sending!
@@ -103,8 +103,8 @@ module ActionDispatch # :nodoc:
 
       def body
         @str_body ||= begin
-          buf = ''
-            each { |chunk| buf << chunk }
+          buf = ""
+          each { |chunk| buf << chunk }
           buf
         end
       end
@@ -224,8 +224,10 @@ module ActionDispatch # :nodoc:
 
     # Sets the HTTP content type.
     def content_type=(content_type)
-      header_info = parse_content_type
-      set_content_type content_type.to_s, header_info.charset || self.class.default_charset
+      return unless content_type
+      new_header_info = parse_content_type(content_type.to_s)
+      prev_header_info = parsed_content_type_header
+      set_content_type new_header_info.mime_type, new_header_info.charset || prev_header_info.charset || self.class.default_charset
     end
 
     # Sets the HTTP response's content MIME type. For example, in the controller
@@ -238,7 +240,7 @@ module ActionDispatch # :nodoc:
     # information.
 
     def content_type
-      parse_content_type.mime_type
+      parsed_content_type_header.mime_type
     end
 
     def sending_file=(v)
@@ -253,7 +255,7 @@ module ActionDispatch # :nodoc:
     #   response.charset = 'utf-16' # => 'utf-16'
     #   response.charset = nil      # => 'utf-8'
     def charset=(charset)
-      header_info = parse_content_type
+      header_info = parsed_content_type_header
       if false == charset
         set_header CONTENT_TYPE, header_info.mime_type
       else
@@ -265,7 +267,7 @@ module ActionDispatch # :nodoc:
     # The charset of the response. HTML wants to know the encoding of the
     # content you're giving them, so we need to send that along.
     def charset
-      header_info = parse_content_type
+      header_info = parsed_content_type_header
       header_info.charset || self.class.default_charset
     end
 
@@ -329,7 +331,7 @@ module ActionDispatch # :nodoc:
 
       # Stream the file's contents if Rack::Sendfile isn't present.
       def each
-        File.open(to_path, 'rb') do |file|
+        File.open(to_path, "rb") do |file|
           while chunk = file.read(16384)
             yield chunk
           end
@@ -389,7 +391,7 @@ module ActionDispatch # :nodoc:
       if header = get_header(SET_COOKIE)
         header = header.split("\n") if header.respond_to?(:to_str)
         header.each do |cookie|
-          if pair = cookie.split(';').first
+          if pair = cookie.split(";").first
             key, value = pair.split("=").map { |v| Rack::Utils.unescape(v) }
             cookies[key] = value
           end
@@ -403,8 +405,7 @@ module ActionDispatch # :nodoc:
     ContentTypeHeader = Struct.new :mime_type, :charset
     NullContentTypeHeader = ContentTypeHeader.new nil, nil
 
-    def parse_content_type
-      content_type = get_header CONTENT_TYPE
+    def parse_content_type(content_type)
       if content_type
         type, charset = content_type.split(/;\s*charset=/)
         type = nil if type.empty?
@@ -414,8 +415,14 @@ module ActionDispatch # :nodoc:
       end
     end
 
+    # Small internal convenience method to get the parsed version of the current
+    # content type header.
+    def parsed_content_type_header
+      parse_content_type(get_header(CONTENT_TYPE))
+    end
+
     def set_content_type(content_type, charset)
-      type = (content_type || '').dup
+      type = (content_type || "").dup
       type << "; charset=#{charset}" if charset
       set_header CONTENT_TYPE, type
     end
@@ -450,7 +457,7 @@ module ActionDispatch # :nodoc:
     def assign_default_content_type_and_charset!
       return if content_type
 
-      ct = parse_content_type
+      ct = parsed_content_type_header
       set_content_type(ct.mime_type || Mime[:html].to_s,
                        ct.charset || self.class.default_charset)
     end
@@ -475,7 +482,7 @@ module ActionDispatch # :nodoc:
       end
 
       def respond_to?(method, include_private = false)
-        if method.to_s == 'to_path'
+        if method.to_s == "to_path"
           @response.stream.respond_to?(method)
         else
           super
@@ -494,7 +501,7 @@ module ActionDispatch # :nodoc:
     def handle_no_content!
       if NO_CONTENT_CODES.include?(@status)
         @header.delete CONTENT_TYPE
-        @header.delete 'Content-Length'
+        @header.delete "Content-Length"
       end
     end