1 files changed, 17 insertions, 1 deletions
diff --git a/actionpack/lib/action_dispatch/http/parameters.rb b/actionpack/lib/action_dispatch/http/parameters.rb
index f25e50f9f3..31ef0af791 100644
--- a/actionpack/lib/action_dispatch/http/parameters.rb
+++ b/actionpack/lib/action_dispatch/http/parameters.rb
@@ -8,7 +8,7 @@ module ActionDispatch
       DEFAULT_PARSERS = {
         Mime[:json].symbol => -> (raw_post) {
           data = ActiveSupport::JSON.decode(raw_post)
-          data.is_a?(Hash) ? data : {_json: data}
+          data.is_a?(Hash) ? data : { _json: data }
         }
       }
 
@@ -37,6 +37,7 @@ module ActionDispatch
                    query_parameters.dup
                  end
         params.merge!(path_parameters)
+        params = set_custom_encoding(params)
         set_header("action_dispatch.request.parameters", params)
         params
       end
@@ -64,6 +65,21 @@ module ActionDispatch
 
       private
 
+        def set_custom_encoding(params)
+          action = params[:action]
+          params.each do |k, v|
+            if v.is_a?(String) && v.encoding != encoding_template(action, k)
+              params[k] = v.force_encoding(encoding_template(action, k))
+            end
+          end
+
+          params
+        end
+
+        def encoding_template(action, param)
+          controller_class.encoding_for_param(action, param)
+        end
+
         def parse_formatted_parameters(parsers)
           return yield if content_length.zero? || content_mime_type.nil?