From 46e84d5b104ca5dca88829c9db7941f0e6ce7aaa Mon Sep 17 00:00:00 2001
From: Eugene Kenny <elkenny@gmail.com>
Date: Sat, 18 May 2019 22:49:32 +0100
Subject: Return parameters enumerator from transform_keys/!

Previously calling `ActionController::Parameters#transform_keys/!`
without passing a block would return an enumerator for the underlying
hash, which was inconsistent with the behaviour when a block was passed:

    ActionController::Parameters.new(foo: "bar").transform_keys { |k| k }
    => <ActionController::Parameters {"foo"=>"bar"} permitted: false>
    ActionController::Parameters.new(foo: "bar").transform_keys.each { |k| k }
    => {"foo"=>"bar"}

An enumerator for the parameters is now returned instead, ensuring that
evaluating it produces another parameters object instead of a hash:

    ActionController::Parameters.new(foo: "bar").transform_keys.each { |k| k }
    => <ActionController::Parameters {"foo"=>"bar"} permitted: false>
---
 actionpack/lib/action_controller/metal/strong_parameters.rb | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

(limited to 'actionpack/lib/action_controller')

diff --git a/actionpack/lib/action_controller/metal/strong_parameters.rb b/actionpack/lib/action_controller/metal/strong_parameters.rb
index 8bde82ccca..016a633f71 100644
--- a/actionpack/lib/action_controller/metal/strong_parameters.rb
+++ b/actionpack/lib/action_controller/metal/strong_parameters.rb
@@ -679,18 +679,16 @@ module ActionController
     # Returns a new <tt>ActionController::Parameters</tt> instance with the
     # results of running +block+ once for every key. The values are unchanged.
     def transform_keys(&block)
-      if block
-        new_instance_with_inherited_permitted_status(
-          @parameters.transform_keys(&block)
-        )
-      else
-        @parameters.transform_keys
-      end
+      return to_enum(:transform_keys) unless block_given?
+      new_instance_with_inherited_permitted_status(
+        @parameters.transform_keys(&block)
+      )
     end
 
     # Performs keys transformation and returns the altered
     # <tt>ActionController::Parameters</tt> instance.
     def transform_keys!(&block)
+      return to_enum(:transform_keys!) unless block_given?
       @parameters.transform_keys!(&block)
       self
     end
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