1 files changed, 31 insertions, 14 deletions

diff --git a/actionpack/lib/action_dispatch/middleware/public_exceptions.rb b/actionpack/lib/action_dispatch/middleware/public_exceptions.rb
index 85b8d178bf..53bedaa40a 100644
--- a/actionpack/lib/action_dispatch/middleware/public_exceptions.rb
+++ b/actionpack/lib/action_dispatch/middleware/public_exceptions.rb
@@ -1,5 +1,4 @@
 module ActionDispatch
-  # A simple Rack application that renders exceptions in the given public path.
   class PublicExceptions
     attr_accessor :public_path
 
@@ -8,23 +7,41 @@ module ActionDispatch
     end
 
     def call(env)
-      status      = env["PATH_INFO"][1..-1]
-      locale_path = "#{public_path}/#{status}.#{I18n.locale}.html" if I18n.locale
-      path        = "#{public_path}/#{status}.html"
-
-      if locale_path && File.exist?(locale_path)
-        render(status, File.read(locale_path))
-      elsif File.exist?(path)
-        render(status, File.read(path))
+      exception    = env["action_dispatch.exception"]
+      status       = env["PATH_INFO"][1..-1]
+      request      = ActionDispatch::Request.new(env)
+      content_type = request.formats.first
+      body         = { :status => status, :error => exception.message }
+
+      render(status, content_type, body)
+    end
+
+    private
+
+    def render(status, content_type, body)
+      format = content_type && "to_#{content_type.to_sym}"
+      if format && body.respond_to?(format)
+        render_format(status, content_type, body.public_send(format))
       else
-        [404, { "X-Cascade" => "pass" }, []]
+        render_html(status)
       end
     end
 
-    private
+    def render_format(status, content_type, body)
+      [status, {'Content-Type' => "#{content_type}; charset=#{ActionDispatch::Response.default_charset}",
+                'Content-Length' => body.bytesize.to_s}, [body]]
+    end
+
+    def render_html(status)
+      found = false
+      path = "#{public_path}/#{status}.#{I18n.locale}.html" if I18n.locale
+      path = "#{public_path}/#{status}.html" unless path && (found = File.exist?(path))
 
-    def render(status, body)
-      [status, {'Content-Type' => "text/html; charset=#{Response.default_charset}", 'Content-Length' => body.bytesize.to_s}, [body]]
+      if found || File.exist?(path)
+        render_format(status, 'text/html', File.read(path))
+      else
+        [404, { "X-Cascade" => "pass" }, []]
+      end
     end
   end
-end
\ No newline at end of file
+end