avoid calling custom_encoding_for when unused

if the action does not use a custom encoding, then we can skip checking if we need to fix the encoding on any of the parameters.

Instead of asking the controller about each of the parameters, we can ask the controller to tell us what params to convert once. If the controller returns nothing, we have no work to do.

actionpack/lib/action_controller/metal.rb

@@ -135,7 +135,7 @@ module ActionController
       end
     end
 
-    def self.custom_encoding_for(action, param) # :nodoc:
+    def self.action_encoding_template(action) # :nodoc:
       false
     end
 

actionpack/lib/action_controller/metal/parameter_encoding.rb

@@ -15,8 +15,10 @@ module ActionController
         @_parameter_encodings = Hash.new { |h, k| h[k] = {} }
       end
 
-      def custom_encoding_for(action, param) # :nodoc:
-        @_parameter_encodings[action.to_s][param.to_s]
+      def action_encoding_template(action) # :nodoc:
+        if @_parameter_encodings.has_key?(action.to_s)
+          @_parameter_encodings[action.to_s]
+        end
       end
 
       # Specify that a given action's parameters should all be encoded as

actionpack/lib/action_dispatch/http/request.rb

@@ -76,7 +76,7 @@ module ActionDispatch
     PASS_NOT_FOUND = Class.new { # :nodoc:
       def self.action(_); self; end
       def self.call(_); [404, { "X-Cascade" => "pass" }, []]; end
-      def self.custom_encoding_for(action, param); nil; end
+      def self.action_encoding_template(action); false; end
     }
 
     def controller_class

actionpack/lib/action_dispatch/request/utils.rb

@@ -80,20 +80,19 @@ module ActionDispatch
 
       class CustomParamEncoder # :nodoc:
         def self.encode(request, params, controller, action)
-          return params unless controller && controller.valid_encoding?
-
+          return params unless controller && controller.valid_encoding? && encoding_template = action_encoding_template(request, controller, action)
           params.except(:controller, :action).each do |key, value|
             ActionDispatch::Request::Utils.each_param_value(value) do |param|
-              if desired_encoding = custom_encoding_for(request, controller, action, key)
-                param.force_encoding(desired_encoding)
+              if encoding_template[key.to_s]
+                param.force_encoding(encoding_template[key.to_s])
               end
             end
           end
           params
         end
 
-        def self.custom_encoding_for(request, controller, action, param)
-          request.controller_class_for(controller).custom_encoding_for(action, param)
+        def self.action_encoding_template(request, controller, action) # :nodoc:
+          request.controller_class_for(controller).action_encoding_template(action)
         rescue MissingController
           nil
         end

actionpack/test/dispatch/routing_test.rb

@@ -4607,6 +4607,21 @@ class TestInvalidUrls < ActionDispatch::IntegrationTest
       assert_response :ok
     end
   end
+
+  test "does not encode params besides id" do
+    with_routing do |set|
+      set.draw do
+        get "/foo/show(/:id)", to: "test_invalid_urls/foo#show"
+        get "/bar/show(/:id)", controller: "test_invalid_urls/foo", action: "show"
+      end
+
+      get "/foo/show/%E2%EF%BF%BD%A6?something_else=%E2%EF%BF%BD%A6"
+      assert_response :bad_request
+
+      get "/foo/show/%E2%EF%BF%BD%A6?something_else=%E2%EF%BF%BD%A6"
+      assert_response :bad_request
+    end
+  end
 end
 
 class TestOptionalRootSegments < ActionDispatch::IntegrationTest