Merge branch 'rm-use-active-model-correctly'

Closes #18646

6 files changed, 103 insertions, 28 deletions

diff --git a/actionview/lib/action_view/helpers/tags.rb b/actionview/lib/action_view/helpers/tags.rb
index 45c75d10c0..a4f6eb0150 100644
--- a/actionview/lib/action_view/helpers/tags.rb
+++ b/actionview/lib/action_view/helpers/tags.rb
@@ -5,6 +5,7 @@ module ActionView
 
       eager_autoload do
         autoload :Base
+        autoload :Translator
         autoload :CheckBox
         autoload :CollectionCheckBoxes
         autoload :CollectionRadioButtons
diff --git a/actionview/lib/action_view/helpers/tags/label.rb b/actionview/lib/action_view/helpers/tags/label.rb
index 08a23e497e..b31d5fda66 100644
--- a/actionview/lib/action_view/helpers/tags/label.rb
+++ b/actionview/lib/action_view/helpers/tags/label.rb
@@ -15,20 +15,10 @@ module ActionView
 
           def translation
             method_and_value = @tag_value.present? ? "#{@method_name}.#{@tag_value}" : @method_name
-            @object_name.gsub!(/\[(.*)_attributes\]\[\d+\]/, '.\1')
-
-            if object.respond_to?(:to_model)
-              key = object.model_name.i18n_key
-              i18n_default = ["#{key}.#{method_and_value}".to_sym, ""]
-            end
-
-            i18n_default ||= ""
-            content = I18n.t("#{@object_name}.#{method_and_value}", :default => i18n_default, :scope => "helpers.label").presence
-
-            content ||= if object && object.class.respond_to?(:human_attribute_name)
-                          object.class.human_attribute_name(method_and_value)
-                        end
 
+            content ||= Translator
+              .new(object, @object_name, method_and_value, scope: "helpers.label")
+              .translate
             content ||= @method_name.humanize
 
             content
diff --git a/actionview/lib/action_view/helpers/tags/placeholderable.rb b/actionview/lib/action_view/helpers/tags/placeholderable.rb
index ae67bc13af..cf7b117614 100644
--- a/actionview/lib/action_view/helpers/tags/placeholderable.rb
+++ b/actionview/lib/action_view/helpers/tags/placeholderable.rb
@@ -7,24 +7,12 @@ module ActionView
 
           if tag_value = @options[:placeholder]
             placeholder = tag_value if tag_value.is_a?(String)
-
-            object_name = @object_name.gsub(/\[(.*)_attributes\]\[\d+\]/, '.\1')
             method_and_value = tag_value.is_a?(TrueClass) ? @method_name : "#{@method_name}.#{tag_value}"
 
-            if object.respond_to?(:to_model)
-              key = object.class.model_name.i18n_key
-              i18n_default = ["#{key}.#{method_and_value}".to_sym, ""]
-            end
-
-            i18n_default ||= ""
-            placeholder ||= I18n.t("#{object_name}.#{method_and_value}", :default => i18n_default, :scope => "helpers.placeholder").presence
-
-            placeholder ||= if object && object.class.respond_to?(:human_attribute_name)
-                          object.class.human_attribute_name(method_and_value)
-                        end
-
+            placeholder ||= Tags::Translator
+              .new(object, @object_name, method_and_value, scope: "helpers.placeholder")
+              .translate
             placeholder ||= @method_name.humanize
-
             @options[:placeholder] = placeholder
           end
         end
diff --git a/actionview/lib/action_view/helpers/tags/translator.rb b/actionview/lib/action_view/helpers/tags/translator.rb
new file mode 100644
index 0000000000..829679851c
--- /dev/null
+++ b/actionview/lib/action_view/helpers/tags/translator.rb
@@ -0,0 +1,38 @@
+module ActionView
+  module Helpers
+    module Tags # :nodoc:
+      class Translator # :nodoc:
+        def initialize(object, object_name, method_and_value, scope:)
+          @object_name = object_name.gsub(/\[(.*)_attributes\]\[\d+\]/, '.\1')
+          @method_and_value = method_and_value
+          @scope = scope
+          @model = object.respond_to?(:to_model) ? object.to_model : object
+        end
+
+        def translate
+          translated_attribute = I18n.t("#{object_name}.#{method_and_value}", default: i18n_default, scope: scope).presence
+          translated_attribute || human_attribute_name
+        end
+
+        private
+
+        attr_reader :object_name, :method_and_value, :scope, :model
+
+        def i18n_default
+          if model
+            key = model.model_name.i18n_key
+            ["#{key}.#{method_and_value}".to_sym, ""]
+          else
+            ""
+          end
+        end
+
+        def human_attribute_name
+          if model && model.class.respond_to?(:human_attribute_name)
+            model.class.human_attribute_name(method_and_value)
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/actionview/test/lib/controller/fake_models.rb b/actionview/test/lib/controller/fake_models.rb
index 789b1d198b..65c68fc34a 100644
--- a/actionview/test/lib/controller/fake_models.rb
+++ b/actionview/test/lib/controller/fake_models.rb
@@ -54,6 +54,22 @@ class Post < Struct.new(:title, :author_name, :body, :secret, :persisted, :writt
   def tags_attributes=(attributes); end
 end
 
+class PostDelegator < Post
+  def to_model
+    PostDelegate.new
+  end
+end
+
+class PostDelegate < Post
+  def self.human_attribute_name(attribute)
+    "Delegate #{super}"
+  end
+
+  def model_name
+    ActiveModel::Name.new(self.class)
+  end
+end
+
 class Comment
   extend ActiveModel::Naming
   include ActiveModel::Conversion
diff --git a/actionview/test/template/form_helper_test.rb b/actionview/test/template/form_helper_test.rb
index dccf6a2090..1ed4fbafcf 100644
--- a/actionview/test/template/form_helper_test.rb
+++ b/actionview/test/template/form_helper_test.rb
@@ -40,6 +40,9 @@ class FormHelperTest < ActionView::TestCase
           },
           tag: {
             value: "Tag"
+          },
+          post_delegate: {
+            title: 'Delegate model_name title'
           }
         }
       }
@@ -81,6 +84,9 @@ class FormHelperTest < ActionView::TestCase
               body: "Write body here"
             }
           },
+          post_delegate: {
+            title: 'Delegate model_name title'
+          },
           tag: {
             value: "Tag"
           }
@@ -117,6 +123,10 @@ class FormHelperTest < ActionView::TestCase
     @post.tags = []
     @post.tags << Tag.new
 
+    @post_delegator = PostDelegator.new
+
+    @post_delegator.title = 'Hello World'
+
     @car = Car.new("#000FFF")
   end
 
@@ -337,6 +347,22 @@ class FormHelperTest < ActionView::TestCase
     )
   end
 
+  def test_label_with_to_model
+    assert_dom_equal(
+      %{<label for="post_delegator_title">Delegate Title</label>},
+      label(:post_delegator, :title)
+    )
+  end
+
+  def test_label_with_to_model_and_overriden_model_name
+    with_locale :label do
+      assert_dom_equal(
+        %{<label for="post_delegator_title">Delegate model_name title</label>},
+        label(:post_delegator, :title)
+      )
+    end
+  end
+
   def test_text_field_placeholder_without_locales
     with_locale :placeholder do
       assert_dom_equal('<input id="post_body" name="post[body]" placeholder="Body" type="text" value="Back to the hill and over it again!" />', text_field(:post, :body, placeholder: true))
@@ -349,12 +375,28 @@ class FormHelperTest < ActionView::TestCase
     end
   end
 
+  def test_text_field_placeholder_with_locales_and_to_model
+    with_locale :placeholder do
+      assert_dom_equal(
+        '<input id="post_delegator_title" name="post_delegator[title]" placeholder="Delegate model_name title" type="text" value="Hello World" />',
+        text_field(:post_delegator, :title, placeholder: true)
+      )
+    end
+  end
+
   def test_text_field_placeholder_with_human_attribute_name
     with_locale :placeholder do
       assert_dom_equal('<input id="post_cost" name="post[cost]" placeholder="Total cost" type="text" />', text_field(:post, :cost, placeholder: true))
     end
   end
 
+  def test_text_field_placeholder_with_human_attribute_name_and_to_model
+    assert_dom_equal(
+      '<input id="post_delegator_title" name="post_delegator[title]" placeholder="Delegate Title" type="text" value="Hello World" />',
+      text_field(:post_delegator, :title, placeholder: true)
+    )
+  end
+
   def test_text_field_placeholder_with_string_value
     with_locale :placeholder do
       assert_dom_equal('<input id="post_cost" name="post[cost]" placeholder="HOW MUCH?" type="text" />', text_field(:post, :cost, placeholder: "HOW MUCH?"))