1 files changed, 13 insertions, 5 deletions
diff --git a/actionpack/lib/action_dispatch/middleware/params_parser.rb b/actionpack/lib/action_dispatch/middleware/params_parser.rb
index e83cf9236b..32ccb5c931 100644
--- a/actionpack/lib/action_dispatch/middleware/params_parser.rb
+++ b/actionpack/lib/action_dispatch/middleware/params_parser.rb
@@ -2,11 +2,13 @@ require 'active_support/json'
 
 module ActionDispatch
   class ParamsParser
-    ActionController::Base.param_parsers[Mime::XML] = :xml_simple
-    ActionController::Base.param_parsers[Mime::JSON] = :json
+    DEFAULT_PARSERS = {
+      Mime::XML => :xml_simple,
+      Mime::JSON => :json
+    }
 
-    def initialize(app)
-      @app = app
+    def initialize(app, parsers = {})
+      @app, @parsers = app, DEFAULT_PARSERS.merge(parsers)
     end
 
     def call(env)
@@ -24,7 +26,7 @@ module ActionDispatch
         return false if request.content_length.zero?
 
         mime_type = content_type_from_legacy_post_data_format_header(env) || request.content_type
-        strategy = ActionController::Base.param_parsers[mime_type]
+        strategy = @parsers[mime_type]
 
         return false unless strategy
 
@@ -47,6 +49,8 @@ module ActionDispatch
             false
         end
       rescue Exception => e # YAML, XML or Ruby code block errors
+        logger.debug "Error occurred while parsing request parameters.\nContents:\n\n#{request.raw_post}"
+
         raise
           { "body" => request.raw_post,
             "content_type" => request.content_type,
@@ -67,5 +71,9 @@ module ActionDispatch
 
         nil
       end
+
+      def logger
+        defined?(Rails.logger) ? Rails.logger : Logger.new($stderr)
+      end
   end
 end