5 files changed, 40 insertions, 3 deletions
diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index 7d400eaa22..20321eece4 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,3 +1,12 @@
+*   Adds support for including ActionController::Cookies in API controllers.
+    Previously, including the module would raise when trying to define
+    a `cookies` helper method. Skip calling #helper_method if it is not
+    defined -- if we don't have helpers, we needn't define one.
+
+    Fixes #24304
+
+    *Ryan T. Hosford*
+
 *   ETags: Introduce `Response#strong_etag=` and `#weak_etag=` and analogous
     options for `fresh_when` and `stale?`. `Response#etag=` sets a weak ETag.
 
diff --git a/actionpack/lib/action_controller/metal/conditional_get.rb b/actionpack/lib/action_controller/metal/conditional_get.rb
index f202000347..480e265e44 100644
--- a/actionpack/lib/action_controller/metal/conditional_get.rb
+++ b/actionpack/lib/action_controller/metal/conditional_get.rb
@@ -41,7 +41,7 @@ module ActionController
     # * <tt>:weak_etag</tt> Sets a "weak" ETag validator on the response.
     #   Requests that set If-None-Match header may return a 304 Not Modified
     #   response if it matches the ETag exactly. A weak ETag indicates semantic
-    #   equivalence, not byte-for-byte equality, so they're a good for caching
+    #   equivalence, not byte-for-byte equality, so they're good for caching
     #   HTML pages in browser caches. They can't be used for responses that
     #   must be byte-identical, like serving Range requests within a PDF file.
     # * <tt>:strong_etag</tt> Sets a "strong" ETag validator on the response.
@@ -131,7 +131,7 @@ module ActionController
     # * <tt>:weak_etag</tt> Sets a "weak" ETag validator on the response.
     #   requests that set If-None-Match header may return a 304 Not Modified
     #   response if it matches the ETag exactly. A weak ETag indicates semantic
-    #   equivalence, not byte-for-byte equality, so they're a good for caching
+    #   equivalence, not byte-for-byte equality, so they're good for caching
     #   HTML pages in browser caches. They can't be used for responses that
     #   must be byte-identical, like serving Range requests within a PDF file.
     # * <tt>:strong_etag</tt> Sets a "strong" ETag validator on the response.
diff --git a/actionpack/lib/action_controller/metal/cookies.rb b/actionpack/lib/action_controller/metal/cookies.rb
index f8efb2b076..44925641a1 100644
--- a/actionpack/lib/action_controller/metal/cookies.rb
+++ b/actionpack/lib/action_controller/metal/cookies.rb
@@ -3,7 +3,7 @@ module ActionController #:nodoc:
     extend ActiveSupport::Concern
 
     included do
-      helper_method :cookies
+      helper_method :cookies if defined?(helper_method)
     end
 
     private
diff --git a/actionpack/lib/action_controller/metal/strong_parameters.rb b/actionpack/lib/action_controller/metal/strong_parameters.rb
index 76e3b4d25a..64672de57e 100644
--- a/actionpack/lib/action_controller/metal/strong_parameters.rb
+++ b/actionpack/lib/action_controller/metal/strong_parameters.rb
@@ -184,6 +184,13 @@ module ActionController
     # Returns an unsafe, unfiltered
     # <tt>ActiveSupport::HashWithIndifferentAccess</tt> representation of this
     # parameter.
+    #
+    #   params = ActionController::Parameters.new({
+    #     name: 'Senjougahara Hitagi',
+    #     oddity: 'Heavy stone crab'
+    #   })
+    #   params.to_unsafe_h
+    #   # => {"name"=>"Senjougahara Hitagi", "oddity" => "Heavy stone crab"}
     def to_unsafe_h
       convert_parameters_to_hashes(@parameters, :to_unsafe_h)
     end
diff --git a/actionpack/test/controller/api/with_cookies_test.rb b/actionpack/test/controller/api/with_cookies_test.rb
new file mode 100644
index 0000000000..4491dc9002
--- /dev/null
+++ b/actionpack/test/controller/api/with_cookies_test.rb
@@ -0,0 +1,21 @@
+require 'abstract_unit'
+
+class WithCookiesController < ActionController::API
+  include ActionController::Cookies
+
+  def with_cookies
+    render plain: cookies[:foobar]
+  end
+end
+
+class WithCookiesTest < ActionController::TestCase
+  tests WithCookiesController
+
+  def test_with_cookies
+    request.cookies[:foobar] = 'bazbang'
+
+    get :with_cookies
+
+    assert_equal 'bazbang', response.body
+  end
+end