1 files changed, 51 insertions, 0 deletions
diff --git a/actionpack/lib/action_controller/metal/parameter_encoding.rb b/actionpack/lib/action_controller/metal/parameter_encoding.rb
new file mode 100644
index 0000000000..7a45732d31
--- /dev/null
+++ b/actionpack/lib/action_controller/metal/parameter_encoding.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module ActionController
+  # Specify binary encoding for parameters for a given action.
+  module ParameterEncoding
+    extend ActiveSupport::Concern
+
+    module ClassMethods
+      def inherited(klass) # :nodoc:
+        super
+        klass.setup_param_encode
+      end
+
+      def setup_param_encode # :nodoc:
+        @_parameter_encodings = {}
+      end
+
+      def binary_params_for?(action) # :nodoc:
+        @_parameter_encodings[action.to_s]
+      end
+
+      # Specify that a given action's parameters should all be encoded as
+      # ASCII-8BIT (it "skips" the encoding default of UTF-8).
+      #
+      # For example, a controller would use it like this:
+      #
+      #   class RepositoryController < ActionController::Base
+      #     skip_parameter_encoding :show
+      #
+      #     def show
+      #       @repo = Repository.find_by_filesystem_path params[:file_path]
+      #
+      #       # `repo_name` is guaranteed to be UTF-8, but was ASCII-8BIT, so
+      #       # tag it as such
+      #       @repo_name = params[:repo_name].force_encoding 'UTF-8'
+      #     end
+      #
+      #     def index
+      #       @repositories = Repository.all
+      #     end
+      #   end
+      #
+      # The show action in the above controller would have all parameter values
+      # encoded as ASCII-8BIT. This is useful in the case where an application
+      # must handle data but encoding of the data is unknown, like file system data.
+      def skip_parameter_encoding(action)
+        @_parameter_encodings[action.to_s] = true
+      end
+    end
+  end
+end