Change form_with to generates ids by default

When `form_with` was introduced we disabled the automatic
generation of ids that was enabled in `form_for`. This usually
is not an good idea since labels don't work when the input
doesn't have an id and it made harder to test with Capybara.

You can still disable the automatic generation of ids setting
`config.action_view.form_with_generates_ids` to `false.`

actionview/CHANGELOG.md

@@ -1,3 +1,14 @@
+*   Change `form_with` to generates ids by default.
+
+    When `form_with` was introduced we disabled the automatic generation of ids
+    that was enabled in `form_for`. This usually is not an good idea since labels don't work
+    when the input doesn't have an id and it made harder to test with Capybara.
+
+    You can still disable the automatic generation of ids setting `config.action_view.form_with_generates_ids`
+    to `false.`
+
+    *Nick Pezza*
+
 *   Fix issues with `field_error_proc` wrapping `optgroup` and select divider `option`.
 
     Fixes #31088

actionview/lib/action_view/helpers/form_helper.rb

@@ -478,6 +478,8 @@ def apply_form_for_options!(record, object, options) #:nodoc:
 
       mattr_accessor :form_with_generates_remote_forms, default: true
 
+      mattr_accessor :form_with_generates_ids, default: true
+
       # Creates a form tag based on mixing URLs, scopes, or models.
       #
       #   # Using just a URL:
@@ -640,16 +642,6 @@ def apply_form_for_options!(record, object, options) #:nodoc:
       #
       # Where <tt>@document = Document.find(params[:id])</tt>.
       #
-      # When using labels +form_with+ requires setting the id on the field being
-      # labelled:
-      #
-      #   <%= form_with(model: @post) do |form| %>
-      #     <%= form.label :title %>
-      #     <%= form.text_field :title, id: :post_title %>
-      #   <% end %>
-      #
-      # See +label+ for more on how the +for+ attribute is derived.
-      #
       # === Mixing with other form helpers
       #
       # While +form_with+ uses a FormBuilder object it's possible to mix and
@@ -746,7 +738,6 @@ def apply_form_for_options!(record, object, options) #:nodoc:
       #   end
       def form_with(model: nil, scope: nil, url: nil, format: nil, **options)
         options[:allow_method_names_outside_object] = true
-        options[:skip_default_ids] = true
 
         if model
           url ||= polymorphic_path(model, format: format)
@@ -1044,16 +1035,6 @@ def fields_for(record_name, record_object = nil, options = {}, &block)
       # or model is yielded, so any generated field names are prefixed with
       # either the passed scope or the scope inferred from the <tt>:model</tt>.
       #
-      # When using labels +fields+ requires setting the id on the field being
-      # labelled:
-      #
-      #   <%= fields :comment do |fields| %>
-      #     <%= fields.label :body %>
-      #     <%= fields.text_field :body, id: :comment_body %>
-      #   <% end %>
-      #
-      # See +label+ for more on how the +for+ attribute is derived.
-      #
       # === Mixing with other form helpers
       #
       # While +form_with+ uses a FormBuilder object it's possible to mix and
@@ -1072,7 +1053,6 @@ def fields_for(record_name, record_object = nil, options = {}, &block)
       # FormOptionsHelper#collection_select and DateHelper#datetime_select.
       def fields(scope = nil, model: nil, **options, &block)
         options[:allow_method_names_outside_object] = true
-        options[:skip_default_ids] = true
 
         if model
           scope ||= model_name_from_record_or_class(model).param_key
@@ -1676,7 +1656,7 @@ def to_model
       def initialize(object_name, object, template, options)
         @nested_child_index = {}
         @object_name, @object, @template, @options = object_name, object, template, options
-        @default_options = @options ? @options.slice(:index, :namespace, :skip_default_ids, :allow_method_names_outside_object) : {}
+        @default_options = @options ? @options.slice(:index, :namespace, :allow_method_names_outside_object) : {}
 
         convert_to_legacy_options(@options)
 
@@ -1985,7 +1965,6 @@ def fields_for(record_name, record_object = nil, fields_options = {}, &block)
       # See the docs for the <tt>ActionView::FormHelper.fields</tt> helper method.
       def fields(scope = nil, model: nil, **options, &block)
         options[:allow_method_names_outside_object] = true
-        options[:skip_default_ids] = true
 
         convert_to_legacy_options(options)
 

actionview/lib/action_view/helpers/tags/base.rb

@@ -15,7 +15,6 @@ def initialize(object_name, method_name, template_object, options = {})
 
           @object_name.sub!(/\[\]$/, "") || @object_name.sub!(/\[\]\]$/, "]")
           @object = retrieve_object(options.delete(:object))
-          @skip_default_ids = options.delete(:skip_default_ids)
           @allow_method_names_outside_object = options.delete(:allow_method_names_outside_object)
           @options = options
 
@@ -97,7 +96,7 @@ def add_default_name_and_id(options)
             index = name_and_id_index(options)
             options["name"] = options.fetch("name") { tag_name(options["multiple"], index) }
 
-            unless skip_default_ids?
+            if generate_ids?
               options["id"] = options.fetch("id") { tag_id(index) }
               if namespace = options.delete("namespace")
                 options["id"] = options["id"] ? "#{namespace}_#{options['id']}" : namespace
@@ -183,8 +182,8 @@ def name_and_id_index(options)
             end
           end
 
-          def skip_default_ids?
-            @skip_default_ids
+          def generate_ids?
+            ActionView::Helpers::FormHelper.form_with_generates_ids
           end
       end
     end

actionview/lib/action_view/helpers/tags/collection_check_boxes.rb

@@ -12,7 +12,6 @@ class CheckBoxBuilder < Builder # :nodoc:
           def check_box(extra_html_options = {})
             html_options = extra_html_options.merge(@input_html_options)
             html_options[:multiple] = true
-            html_options[:skip_default_ids] = false
             @template_object.check_box(@object_name, @method_name, html_options, @value, nil)
           end
         end

actionview/lib/action_view/helpers/tags/collection_radio_buttons.rb

@@ -11,7 +11,6 @@ class CollectionRadioButtons < Base # :nodoc:
         class RadioButtonBuilder < Builder # :nodoc:
           def radio_button(extra_html_options = {})
             html_options = extra_html_options.merge(@input_html_options)
-            html_options[:skip_default_ids] = false
             @template_object.radio_button(@object_name, @method_name, @value, html_options)
           end
         end

actionview/lib/action_view/helpers/tags/label.rb

@@ -75,10 +75,6 @@ def render(&block)
           def render_component(builder)
             builder.translation
           end
-
-          def skip_default_ids?
-            false # The id is used as the `for` attribute.
-          end
       end
     end
   end

actionview/lib/action_view/helpers/tags/select.rb

@@ -8,7 +8,7 @@ def initialize(object_name, method_name, template_object, choices, options, html
           @choices = block_given? ? template_object.capture { yield || "" } : choices
           @choices = @choices.to_a if @choices.is_a?(Range)
 
-          @html_options = html_options.except(:skip_default_ids, :allow_method_names_outside_object)
+          @html_options = html_options.except(:allow_method_names_outside_object)
 
           super(object_name, method_name, template_object, options)
         end

actionview/lib/action_view/railtie.rb

@@ -28,6 +28,15 @@ class Railtie < Rails::Engine # :nodoc:
       end
     end
 
+    initializer "action_view.form_with_generates_ids" do |app|
+      ActiveSupport.on_load(:action_view) do
+        form_with_generates_ids = app.config.action_view.delete(:form_with_generates_ids)
+        unless form_with_generates_ids.nil?
+          ActionView::Helpers::FormHelper.form_with_generates_ids = form_with_generates_ids
+        end
+      end
+    end
+
     initializer "action_view.logger" do
       ActiveSupport.on_load(:action_view) { self.logger ||= Rails.logger }
     end

actionview/test/template/form_helper/form_with_test.rb

@@ -314,11 +314,11 @@ def test_form_with
 
     expected = whole_form("/posts/123", "create-post", method: "patch") do
       "<label for='post_title'>The Title</label>" \
-      "<input name='post[title]' type='text' value='Hello World' />" \
-      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />" \
+      "<textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea>" \
       "<input name='post[secret]' type='hidden' value='0' />" \
-      "<input name='post[secret]' checked='checked' type='checkbox' value='1' />" \
-      "<select name='post[category]'><option value='animal'>animal</option>\n<option value='economy'>economy</option>\n<option value='sports'>sports</option></select>" \
+      "<input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret' />" \
+      "<select name='post[category]' id='post_category'><option value='animal'>animal</option>\n<option value='economy'>economy</option>\n<option value='sports'>sports</option></select>" \
       "<input name='commit' data-disable-with='Create post' type='submit' value='Create post' />" \
       "<button name='button' type='submit'>Create post</button>" \
       "<button name='button' type='submit'><span>Create post</span></button>"
@@ -327,6 +327,34 @@ def test_form_with
     assert_dom_equal expected, output_buffer
   end
 
+  def test_form_with_not_outputting_ids
+    old_value = ActionView::Helpers::FormHelper.form_with_generates_ids
+    ActionView::Helpers::FormHelper.form_with_generates_ids = false
+
+    form_with(model: @post, id: "create-post") do |f|
+      concat f.label(:title) { "The Title" }
+      concat f.text_field(:title)
+      concat f.text_area(:body)
+      concat f.check_box(:secret)
+      concat f.select(:category, %w( animal economy sports ))
+      concat f.submit("Create post")
+    end
+
+    expected = whole_form("/posts/123", "create-post", method: "patch") do
+      "<label>The Title</label>" \
+      "<input name='post[title]' type='text' value='Hello World' />" \
+      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[secret]' type='hidden' value='0' />" \
+      "<input name='post[secret]' checked='checked' type='checkbox' value='1' />" \
+      "<select name='post[category]'><option value='animal'>animal</option>\n<option value='economy'>economy</option>\n<option value='sports'>sports</option></select>" \
+      "<input name='commit' data-disable-with='Create post' type='submit' value='Create post' />"
+    end
+
+    assert_dom_equal expected, output_buffer
+  ensure
+    ActionView::Helpers::FormHelper.form_with_generates_ids = old_value
+  end
+
   def test_form_with_only_url_on_create
     form_with(url: "/posts") do |f|
       concat f.label :title, "Label me"
@@ -335,7 +363,7 @@ def test_form_with_only_url_on_create
 
     expected = whole_form("/posts") do
       '<label for="title">Label me</label>' \
-      '<input type="text" name="title">'
+      '<input type="text" name="title" id="title">'
     end
 
     assert_dom_equal expected, output_buffer
@@ -349,7 +377,7 @@ def test_form_with_only_url_on_update
 
     expected = whole_form("/posts/123") do
       '<label for="title">Label me</label>' \
-      '<input type="text" name="title">'
+      '<input type="text" name="title" id="title">'
     end
 
     assert_dom_equal expected, output_buffer
@@ -361,7 +389,7 @@ def test_form_with_general_attributes
     end
 
     expected = whole_form("/posts/123") do
-      '<input type="text" name="no_model_to_back_this_badboy">'
+      '<input type="text" name="no_model_to_back_this_badboy" id="no_model_to_back_this_badboy" >'
     end
 
     assert_dom_equal expected, output_buffer
@@ -373,7 +401,7 @@ def test_form_with_attribute_not_on_model
     end
 
     expected = whole_form("/posts/123", method: :patch) do
-      '<input type="text" name="post[this_dont_exist_on_post]">'
+      '<input type="text" name="post[this_dont_exist_on_post]" id="post_this_dont_exist_on_post" >'
     end
 
     assert_dom_equal expected, output_buffer
@@ -391,8 +419,8 @@ def test_form_with_doesnt_call_private_or_protected_properties_on_form_object_sk
     end.new
 
     form_with(model: obj, scope: "other_name", url: "/", id: "edit-other-name") do |f|
-      assert_dom_equal '<input type="hidden" name="other_name[private_property]">', f.hidden_field(:private_property)
-      assert_dom_equal '<input type="hidden" name="other_name[protected_property]">', f.hidden_field(:protected_property)
+      assert_dom_equal '<input type="hidden" name="other_name[private_property]" id="other_name_private_property">', f.hidden_field(:private_property)
+      assert_dom_equal '<input type="hidden" name="other_name[protected_property]"  id="other_name_protected_property">', f.hidden_field(:protected_property)
     end
   end
 
@@ -459,7 +487,7 @@ def post.id; 1; end
       "<label for='post_active_false'>" \
       "<input checked='checked' name='post[active]' type='radio' value='false' id='post_active_false' />" \
       "false</label>" \
-      "<input name='post[id]' type='hidden' value='1' />"
+      "<input name='post[id]' type='hidden' value='1' id='post_id' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -557,7 +585,7 @@ def post.id; 1; end
       "<label for='post_tag_ids_3'>" \
       "<input checked='checked' name='post[tag_ids][]' type='checkbox' value='3' id='post_tag_ids_3' />" \
       "Tag 3</label>" \
-      "<input name='post[id]' type='hidden' value='1' />"
+      "<input name='post[id]' type='hidden' value='1' id='post_id' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -587,7 +615,7 @@ def test_form_with_with_file_field_generate_multipart
     end
 
     expected = whole_form("/posts/123", "create-post", method: "patch", multipart: true) do
-      "<input name='post[file]' type='file' />"
+      "<input name='post[file]' type='file' id='post_file' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -601,7 +629,7 @@ def test_fields_with_file_field_generate_multipart
     end
 
     expected = whole_form("/posts/123", method: "patch", multipart: true) do
-      "<input name='post[comment][file]' type='file' />"
+      "<input name='post[comment][file]' type='file' id='post_comment_file'/>"
     end
 
     assert_dom_equal expected, output_buffer
@@ -640,7 +668,7 @@ def test_form_with_with_model_using_relative_model_naming
     end
 
     expected = whole_form("/posts/44", method: "patch") do
-      "<input name='post[title]' type='text' value='And his name will be forty and four.' />" \
+      "<input name='post[title]' type='text' value='And his name will be forty and four.' id='post_title' />" \
       "<input name='commit' data-disable-with='Edit post' type='submit' value='Edit post' />"
     end
 
@@ -658,10 +686,10 @@ def test_form_with_with_symbol_scope
 
     expected = whole_form("/posts/123", "create-post", method: "patch") do
       "<label for='other_name_title' class='post_title'>Title</label>" \
-      "<input name='other_name[title]' value='Hello World' type='text' />" \
-      "<textarea name='other_name[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='other_name[title]' value='Hello World' type='text' id='other_name_title' />" \
+      "<textarea name='other_name[body]' id='other_name_body'>\nBack to the hill and over it again!</textarea>" \
       "<input name='other_name[secret]' value='0' type='hidden' />" \
-      "<input name='other_name[secret]' checked='checked' value='1' type='checkbox' />" \
+      "<input name='other_name[secret]' checked='checked' value='1' type='checkbox' id='other_name_secret' />" \
       "<input name='commit' value='Create post' data-disable-with='Create post' type='submit' />"
     end
 
@@ -676,10 +704,10 @@ def test_form_with_with_method_as_part_of_html_options
     end
 
     expected = whole_form("/", "create-post", method: "delete") do
-      "<input name='post[title]' type='text' value='Hello World' />" \
-      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />" \
+      "<textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea>" \
       "<input name='post[secret]' type='hidden' value='0' />" \
-      "<input name='post[secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret'/>"
     end
 
     assert_dom_equal expected, output_buffer
@@ -693,10 +721,10 @@ def test_form_with_with_method
     end
 
     expected = whole_form("/", "create-post", method: "delete") do
-      "<input name='post[title]' type='text' value='Hello World' />" \
-      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />" \
+      "<textarea name='post[body]' id='post_body' >\nBack to the hill and over it again!</textarea>" \
       "<input name='post[secret]' type='hidden' value='0' />" \
-      "<input name='post[secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -710,7 +738,7 @@ def test_form_with_with_search_field
     end
 
     expected = whole_form("/search", "search-post", method: "get") do
-      "<input name='post[title]' type='search' />"
+      "<input name='post[title]' type='search' id='post_title' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -724,10 +752,10 @@ def test_form_with_enables_remote_by_default
     end
 
     expected = whole_form("/", "create-post", method: "patch") do
-      "<input name='post[title]' type='text' value='Hello World' />" \
-      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />" \
+      "<textarea name='post[body]' id='post_body' >\nBack to the hill and over it again!</textarea>" \
       "<input name='post[secret]' type='hidden' value='0' />" \
-      "<input name='post[secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -744,10 +772,10 @@ def test_form_is_not_remote_by_default_if_form_with_generates_remote_forms_is_fa
     end
 
     expected = whole_form("/", "create-post", method: "patch", local: true) do
-      "<input name='post[title]' type='text' value='Hello World' />" \
-      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />" \
+      "<textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea>" \
       "<input name='post[secret]' type='hidden' value='0' />" \
-      "<input name='post[secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -761,7 +789,7 @@ def test_form_with_skip_enforcing_utf8_true
     end
 
     expected = whole_form("/", skip_enforcing_utf8: true) do
-      "<input name='post[title]' type='text' value='Hello World' />"
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -773,7 +801,7 @@ def test_form_with_skip_enforcing_utf8_false
     end
 
     expected = whole_form("/", skip_enforcing_utf8: false) do
-      "<input name='post[title]' type='text' value='Hello World' />"
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -787,10 +815,10 @@ def test_form_with_without_object
     end
 
     expected = whole_form("/", "create-post") do
-      "<input name='post[title]' type='text' value='Hello World' />" \
-      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />" \
+      "<textarea name='post[body]' id='post_body' >\nBack to the hill and over it again!</textarea>" \
       "<input name='post[secret]' type='hidden' value='0' />" \
-      "<input name='post[secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -806,10 +834,10 @@ def test_form_with_with_index
 
     expected = whole_form("/posts/123", method: "patch") do
       "<label for='post_123_title'>Title</label>" \
-      "<input name='post[123][title]' type='text' value='Hello World' />" \
-      "<textarea name='post[123][body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[123][title]' type='text' value='Hello World' id='post_123_title' />" \
+      "<textarea name='post[123][body]' id='post_123_body'>\nBack to the hill and over it again!</textarea>" \
       "<input name='post[123][secret]' type='hidden' value='0' />" \
-      "<input name='post[123][secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[123][secret]' checked='checked' type='checkbox' value='1' id='post_123_secret' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -823,10 +851,10 @@ def test_form_with_with_nil_index_option_override
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<input name='post[][title]' type='text' value='Hello World' />" \
-      "<textarea name='post[][body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[][title]' type='text' value='Hello World' id='post__title' />" \
+      "<textarea name='post[][body]' id='post__body' >\nBack to the hill and over it again!</textarea>" \
       "<input name='post[][secret]' type='hidden' value='0' />" \
-      "<input name='post[][secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[][secret]' checked='checked' type='checkbox' value='1' id='post__secret' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -841,7 +869,7 @@ def test_form_with_label_error_wrapping
 
     expected = whole_form("/posts/123", method: "patch") do
       "<div class='field_with_errors'><label for='post_author_name' class='label'>Author name</label></div>" \
-      "<div class='field_with_errors'><input name='post[author_name]' type='text' value='' /></div>" \
+      "<div class='field_with_errors'><input name='post[author_name]' type='text' value='' id='post_author_name' /></div>" \
       "<input name='commit' data-disable-with='Create post' type='submit' value='Create post' />"
     end
 
@@ -859,7 +887,7 @@ def test_form_with_label_error_wrapping_without_conventional_instance_variable
 
     expected = whole_form("/posts/123", method: "patch") do
       "<div class='field_with_errors'><label for='post_author_name' class='label'>Author name</label></div>" \
-      "<div class='field_with_errors'><input name='post[author_name]' type='text' value='' /></div>" \
+      "<div class='field_with_errors'><input name='post[author_name]' type='text' value='' id='post_author_name' /></div>" \
       "<input name='commit' data-disable-with='Create post' type='submit' value='Create post' />"
     end
 
@@ -947,7 +975,7 @@ def test_fields_with_attributes_not_on_model
     end
 
     expected = whole_form("/posts/123", method: :patch) do
-      '<input type="text" name="post[comment][dont_exist_on_model]">'
+      '<input type="text" name="post[comment][dont_exist_on_model]" id="post_comment_dont_exist_on_model" >'
     end
 
     assert_dom_equal expected, output_buffer
@@ -967,7 +995,7 @@ def test_fields_with_attributes_not_on_model_deep_nested
     end
 
     expected = whole_form do
-      '<input name="posts[post][0][comment][1][dont_exist_on_model]" type="text">'
+      '<input name="posts[post][0][comment][1][dont_exist_on_model]" type="text" id="posts_post_0_comment_1_dont_exist_on_model" >'
     end
 
     assert_dom_equal expected, output_buffer
@@ -982,7 +1010,7 @@ def test_nested_fields
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<input name='post[comment][body]' type='text' value='Hello World' />"
+      "<input name='post[comment][body]' type='text' value='Hello World' id='post_comment_body' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1002,7 +1030,7 @@ def test_deep_nested_fields
     end
 
     expected = whole_form do
-      "<input name='posts[post][0][comment][1][name]' type='text' value='comment #1' />"
+      "<input name='posts[post][0][comment][1][name]' type='text' value='comment #1' id='posts_post_0_comment_1_name' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1017,8 +1045,8 @@ def test_nested_fields_with_nested_collections
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<input name='post[123][title]' type='text' value='Hello World' />" \
-      "<input name='post[123][comment][][name]' type='text' value='new comment' />"
+      "<input name='post[123][title]' type='text' value='Hello World' id='post_123_title' />" \
+      "<input name='post[123][comment][][name]' type='text' value='new comment' id='post_123_comment__name' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1033,8 +1061,8 @@ def test_nested_fields_with_index_and_parent_fields
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<input name='post[1][title]' type='text' value='Hello World' />" \
-      "<input name='post[1][comment][1][name]' type='text' value='new comment' />"
+      "<input name='post[1][title]' type='text' value='Hello World' id='post_1_title' />" \
+      "<input name='post[1][comment][1][name]' type='text' value='new comment' id='post_1_comment_1_name' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1048,7 +1076,7 @@ def test_form_with_with_index_and_nested_fields
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<input name='post[1][comment][title]' type='text' value='Hello World' />"
+      "<input name='post[1][comment][title]' type='text' value='Hello World' id='post_1_comment_title' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1062,7 +1090,7 @@ def test_nested_fields_with_index_on_both
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<input name='post[1][comment][5][title]' type='text' value='Hello World' />"
+      "<input name='post[1][comment][5][title]' type='text' value='Hello World' id='post_1_comment_5_title' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1076,7 +1104,7 @@ def test_nested_fields_with_auto_index
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<input name='post[123][comment][title]' type='text' value='Hello World' />"
+      "<input name='post[123][comment][title]' type='text' value='Hello World' id='post_123_comment_title' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1090,7 +1118,7 @@ def test_nested_fields_with_index_radio_button
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<input name='post[comment][5][title]' type='radio' value='hello' />"
+      "<input name='post[comment][5][title]' type='radio' value='hello' id='post_comment_5_title_hello' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1104,7 +1132,7 @@ def test_nested_fields_with_auto_index_on_both
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<input name='post[123][comment][123][title]' type='text' value='Hello World' />"
+      "<input name='post[123][comment][123][title]' type='text' value='Hello World' id='post_123_comment_123_title' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1124,9 +1152,9 @@ def test_nested_fields_with_index_and_auto_index
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<input name='post[123][comment][5][title]' type='text' value='Hello World' />"
+      "<input name='post[123][comment][5][title]' type='text' value='Hello World' id='post_123_comment_5_title' />"
     end + whole_form("/posts/123", method: "patch") do
-      "<input name='post[1][comment][123][title]' type='text' value='Hello World' />"
+      "<input name='post[1][comment][123][title]' type='text' value='Hello World' id='post_1_comment_123_title' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1143,8 +1171,8 @@ def test_nested_fields_with_a_new_record_on_a_nested_attributes_one_to_one_assoc
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-        '<input name="post[author_attributes][name]" type="text" value="new author" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+        '<input name="post[author_attributes][name]" type="text" value="new author" id="post_author_attributes_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1170,9 +1198,9 @@ def test_nested_fields_with_an_existing_record_on_a_nested_attributes_one_to_one
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[author_attributes][name]" type="text" value="author #321" />' \
-      '<input name="post[author_attributes][id]" type="hidden" value="321" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[author_attributes][name]" type="text" value="author #321" id="post_author_attributes_name" />' \
+      '<input name="post[author_attributes][id]" type="hidden" value="321" id="post_author_attributes_id" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1189,9 +1217,9 @@ def test_nested_fields_with_an_existing_record_on_a_nested_attributes_one_to_one
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[author_attributes][name]" type="text" value="author #321" />' \
-      '<input name="post[author_attributes][id]" type="hidden" value="321" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[author_attributes][name]" type="text" value="author #321" id="post_author_attributes_name" />' \
+      '<input name="post[author_attributes][id]" type="hidden" value="321" id="post_author_attributes_id" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1208,8 +1236,8 @@ def test_nested_fields_with_an_existing_record_on_a_nested_attributes_one_to_one
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[author_attributes][name]" type="text" value="author #321" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[author_attributes][name]" type="text" value="author #321" id="post_author_attributes_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1226,8 +1254,8 @@ def test_nested_fields_with_an_existing_record_on_a_nested_attributes_one_to_one
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[author_attributes][name]" type="text" value="author #321" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[author_attributes][name]" type="text" value="author #321" id="post_author_attributes_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1244,9 +1272,9 @@ def test_nested_fields_with_an_existing_record_on_a_nested_attributes_one_to_one
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[author_attributes][name]" type="text" value="author #321" />' \
-      '<input name="post[author_attributes][id]" type="hidden" value="321" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[author_attributes][name]" type="text" value="author #321" id="post_author_attributes_name" />' \
+      '<input name="post[author_attributes][id]" type="hidden" value="321" id="post_author_attributes_id" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1264,9 +1292,9 @@ def test_nested_fields_with_existing_records_on_a_nested_attributes_one_to_one_a
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[author_attributes][id]" type="hidden" value="321" />' \
-      '<input name="post[author_attributes][name]" type="text" value="author #321" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[author_attributes][id]" type="hidden" value="321" id="post_author_attributes_id" />' \
+      '<input name="post[author_attributes][name]" type="text" value="author #321" id="post_author_attributes_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1285,11 +1313,11 @@ def test_nested_fields_with_existing_records_on_a_nested_attributes_collection_a
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" />' \
-      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" />' \
-      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" id="post_comments_attributes_0_id" />' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" id="post_comments_attributes_1_name" />' \
+      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" id="post_comments_attributes_1_id" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1312,11 +1340,11 @@ def test_nested_fields_with_existing_records_on_a_nested_attributes_collection_a
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[author_attributes][name]" type="text" value="author #321" />' \
-      '<input name="post[author_attributes][id]" type="hidden" value="321" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[author_attributes][name]" type="text" value="author #321" id="post_author_attributes_name" />' \
+      '<input name="post[author_attributes][id]" type="hidden" value="321" id="post_author_attributes_id" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" id="post_comments_attributes_1_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1339,10 +1367,10 @@ def test_nested_fields_with_existing_records_on_a_nested_attributes_collection_a
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[author_attributes][name]" type="text" value="author #321" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[author_attributes][name]" type="text" value="author #321" id="post_author_attributes_name" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" id="post_comments_attributes_1_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1365,11 +1393,11 @@ def test_nested_fields_with_existing_records_on_a_nested_attributes_collection_a
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[author_attributes][name]" type="text" value="author #321" />' \
-      '<input name="post[author_attributes][id]" type="hidden" value="321" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[author_attributes][name]" type="text" value="author #321" id="post_author_attributes_name" />' \
+      '<input name="post[author_attributes][id]" type="hidden" value="321" id="post_author_attributes_id" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" id="post_comments_attributes_1_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1388,11 +1416,11 @@ def test_nested_fields_with_existing_records_on_a_nested_attributes_collection_a
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" />' \
-      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" />' \
-      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" id="post_comments_attributes_0_id" />' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" id="post_comments_attributes_1_name" />' \
+      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" id="post_comments_attributes_1_id" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1412,11 +1440,11 @@ def test_nested_fields_with_existing_records_on_a_nested_attributes_collection_a
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" />' \
-      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" id="post_comments_attributes_0_id" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" id="post_comments_attributes_1_id" />' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" id="post_comments_attributes_1_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1435,9 +1463,9 @@ def test_nested_fields_with_new_records_on_a_nested_attributes_collection_associ
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="new comment" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="new comment" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="new comment" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="new comment" id="post_comments_attributes_1_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1456,10 +1484,10 @@ def test_nested_fields_with_existing_and_new_records_on_a_nested_attributes_coll
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #321" />' \
-      '<input name="post[comments_attributes][0][id]" type="hidden" value="321" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="new comment" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #321" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][0][id]" type="hidden" value="321" id="post_comments_attributes_0_id"/>' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="new comment" id="post_comments_attributes_1_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1474,7 +1502,7 @@ def test_nested_fields_with_an_empty_supplied_attributes_collection
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1491,11 +1519,11 @@ def test_nested_fields_with_existing_records_on_a_supplied_nested_attributes_col
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" />' \
-      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" />' \
-      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" id="post_comments_attributes_0_id" />' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" id="post_comments_attributes_1_name" />' \
+      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" id="post_comments_attributes_1_id" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1512,11 +1540,11 @@ def test_nested_fields_arel_like
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" />' \
-      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" />' \
-      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" id="post_comments_attributes_0_id" />' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" id="post_comments_attributes_1_name" />' \
+      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" id="post_comments_attributes_1_id" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1547,11 +1575,11 @@ def test_nested_fields_with_existing_records_on_a_supplied_nested_attributes_col
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" />' \
-      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" />' \
-      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #1" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][0][id]" type="hidden" value="1" id="post_comments_attributes_0_id" />' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="comment #2" id="post_comments_attributes_1_name" />' \
+      '<input name="post[comments_attributes][1][id]" type="hidden" value="2" id="post_comments_attributes_1_id" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1570,10 +1598,10 @@ def test_nested_fields_on_a_nested_attributes_collection_association_yields_only
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[title]" type="text" value="Hello World" />' \
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #321" />' \
-      '<input name="post[comments_attributes][0][id]" type="hidden" value="321" />' \
-      '<input name="post[comments_attributes][1][name]" type="text" value="new comment" />'
+      '<input name="post[title]" type="text" value="Hello World" id="post_title" />' \
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #321" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][0][id]" type="hidden" value="321" id="post_comments_attributes_0_id" />' \
+      '<input name="post[comments_attributes][1][name]" type="text" value="new comment" id="post_comments_attributes_1_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1590,8 +1618,8 @@ def test_nested_fields_with_child_index_option_override_on_a_nested_attributes_c
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[comments_attributes][abc][name]" type="text" value="comment #321" />' \
-      '<input name="post[comments_attributes][abc][id]" type="hidden" value="321" />'
+      '<input name="post[comments_attributes][abc][name]" type="text" value="comment #321" id="post_comments_attributes_abc_name" />' \
+      '<input name="post[comments_attributes][abc][id]" type="hidden" value="321" id="post_comments_attributes_abc_id" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1607,8 +1635,8 @@ def test_nested_fields_with_child_index_as_lambda_option_override_on_a_nested_at
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[comments_attributes][abc][name]" type="text" value="comment #321" />' \
-      '<input name="post[comments_attributes][abc][id]" type="hidden" value="321" />'
+      '<input name="post[comments_attributes][abc][name]" type="text" value="comment #321" id="post_comments_attributes_abc_name" />' \
+      '<input name="post[comments_attributes][abc][id]" type="hidden" value="321" id="post_comments_attributes_abc_id" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1630,8 +1658,8 @@ def test_nested_fields_with_child_index_option_override_on_a_nested_attributes_c
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[comments_attributes][abc][name]" type="text" value="comment #321" />' \
-      '<input name="post[comments_attributes][abc][id]" type="hidden" value="321" />'
+      '<input name="post[comments_attributes][abc][name]" type="text" value="comment #321" id="post_comments_attributes_abc_name" />' \
+      '<input name="post[comments_attributes][abc][id]" type="hidden" value="321" id="post_comments_attributes_abc_id" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1716,18 +1744,18 @@ def test_nested_fields_uses_unique_indices_for_different_collection_associations
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[comments_attributes][0][name]" type="text" value="comment #321" />' \
-      '<input name="post[comments_attributes][0][relevances_attributes][0][value]" type="text" value="commentrelevance #314" />' \
-      '<input name="post[comments_attributes][0][relevances_attributes][0][id]" type="hidden" value="314" />' \
-      '<input name="post[comments_attributes][0][id]" type="hidden" value="321" />' \
-      '<input name="post[tags_attributes][0][value]" type="text" value="tag #123" />' \
-      '<input name="post[tags_attributes][0][relevances_attributes][0][value]" type="text" value="tagrelevance #3141" />' \
-      '<input name="post[tags_attributes][0][relevances_attributes][0][id]" type="hidden" value="3141" />' \
-      '<input name="post[tags_attributes][0][id]" type="hidden" value="123" />' \
-      '<input name="post[tags_attributes][1][value]" type="text" value="tag #456" />' \
-      '<input name="post[tags_attributes][1][relevances_attributes][0][value]" type="text" value="tagrelevance #31415" />' \
-      '<input name="post[tags_attributes][1][relevances_attributes][0][id]" type="hidden" value="31415" />' \
-      '<input name="post[tags_attributes][1][id]" type="hidden" value="456" />'
+      '<input name="post[comments_attributes][0][name]" type="text" value="comment #321" id="post_comments_attributes_0_name" />' \
+      '<input name="post[comments_attributes][0][relevances_attributes][0][value]" type="text" value="commentrelevance #314" id="post_comments_attributes_0_relevances_attributes_0_value" />' \
+      '<input name="post[comments_attributes][0][relevances_attributes][0][id]" type="hidden" value="314" id="post_comments_attributes_0_relevances_attributes_0_id"/>' \
+      '<input name="post[comments_attributes][0][id]" type="hidden" value="321" id="post_comments_attributes_0_id"/>' \
+      '<input name="post[tags_attributes][0][value]" type="text" value="tag #123" id="post_tags_attributes_0_value"/>' \
+      '<input name="post[tags_attributes][0][relevances_attributes][0][value]" type="text" value="tagrelevance #3141" id="post_tags_attributes_0_relevances_attributes_0_value"/>' \
+      '<input name="post[tags_attributes][0][relevances_attributes][0][id]" type="hidden" value="3141" id="post_tags_attributes_0_relevances_attributes_0_id"/>' \
+      '<input name="post[tags_attributes][0][id]" type="hidden" value="123" id="post_tags_attributes_0_id"/>' \
+      '<input name="post[tags_attributes][1][value]" type="text" value="tag #456" id="post_tags_attributes_1_value"/>' \
+      '<input name="post[tags_attributes][1][relevances_attributes][0][value]" type="text" value="tagrelevance #31415" id="post_tags_attributes_1_relevances_attributes_0_value"/>' \
+      '<input name="post[tags_attributes][1][relevances_attributes][0][id]" type="hidden" value="31415" id="post_tags_attributes_1_relevances_attributes_0_id"/>' \
+      '<input name="post[tags_attributes][1][id]" type="hidden" value="456" id="post_tags_attributes_1_id"/>'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1743,7 +1771,7 @@ def test_nested_fields_with_hash_like_model
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      '<input name="post[author_attributes][name]" type="text" value="hash backed author" />'
+      '<input name="post[author_attributes][name]" type="text" value="hash backed author" id="post_author_attributes_name" />'
     end
 
     assert_dom_equal expected, output_buffer
@@ -1757,10 +1785,10 @@ def test_fields
     end
 
     expected =
-      "<input name='post[title]' type='text' value='Hello World' />" \
-      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />" \
+      "<textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea>" \
       "<input name='post[secret]' type='hidden' value='0' />" \
-      "<input name='post[secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret' />"
 
     assert_dom_equal expected, output_buffer
   end
@@ -1773,10 +1801,10 @@ def test_fields_with_index
     end
 
     expected =
-      "<input name='post[123][title]' type='text' value='Hello World' />" \
-      "<textarea name='post[123][body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[123][title]' type='text' value='Hello World' id='post_123_title' />" \
+      "<textarea name='post[123][body]' id='post_123_body'>\nBack to the hill and over it again!</textarea>" \
       "<input name='post[123][secret]' type='hidden' value='0' />" \
-      "<input name='post[123][secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[123][secret]' checked='checked' type='checkbox' value='1' id='post_123_secret' />"
 
     assert_dom_equal expected, output_buffer
   end
@@ -1789,10 +1817,10 @@ def test_fields_with_nil_index_option_override
     end
 
     expected =
-      "<input name='post[][title]' type='text' value='Hello World' />" \
-      "<textarea name='post[][body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[][title]' type='text' value='Hello World' id='post__title' />" \
+      "<textarea name='post[][body]' id='post__body'>\nBack to the hill and over it again!</textarea>" \
       "<input name='post[][secret]' type='hidden' value='0' />" \
-      "<input name='post[][secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[][secret]' checked='checked' type='checkbox' value='1' id='post__secret' />"
 
     assert_dom_equal expected, output_buffer
   end
@@ -1805,10 +1833,10 @@ def test_fields_with_index_option_override
     end
 
     expected =
-      "<input name='post[abc][title]' type='text' value='Hello World' />" \
-      "<textarea name='post[abc][body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[abc][title]' type='text' value='Hello World' id='post_abc_title' />" \
+      "<textarea name='post[abc][body]' id='post_abc_body'>\nBack to the hill and over it again!</textarea>" \
       "<input name='post[abc][secret]' type='hidden' value='0' />" \
-      "<input name='post[abc][secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[abc][secret]' checked='checked' type='checkbox' value='1' id='post_abc_secret' />"
 
     assert_dom_equal expected, output_buffer
   end
@@ -1821,10 +1849,10 @@ def test_fields_without_object
     end
 
     expected =
-      "<input name='post[title]' type='text' value='Hello World' />" \
-      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />" \
+      "<textarea name='post[body]' id='post_body' >\nBack to the hill and over it again!</textarea>" \
       "<input name='post[secret]' type='hidden' value='0' />" \
-      "<input name='post[secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret' />"
 
     assert_dom_equal expected, output_buffer
   end
@@ -1837,10 +1865,10 @@ def test_fields_with_only_object
     end
 
     expected =
-      "<input name='post[title]' type='text' value='Hello World' />" \
-      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />" \
+      "<textarea name='post[body]' id='post_body' >\nBack to the hill and over it again!</textarea>" \
       "<input name='post[secret]' type='hidden' value='0' />" \
-      "<input name='post[secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret' />"
 
     assert_dom_equal expected, output_buffer
   end
@@ -1852,7 +1880,7 @@ def test_fields_object_with_bracketed_name
     end
 
     assert_dom_equal "<label for=\"author_post_title\">Title</label>" \
-    "<input name='author[post][title]' type='text' value='Hello World' />",
+    "<input name='author[post][title]' type='text' value='Hello World' id='author_post_title' id='author_post_1_title' />",
       output_buffer
   end
 
@@ -1863,7 +1891,7 @@ def test_fields_object_with_bracketed_name_and_index
     end
 
     assert_dom_equal "<label for=\"author_post_1_title\">Title</label>" \
-      "<input name='author[post][1][title]' type='text' value='Hello World' />",
+      "<input name='author[post][1][title]' type='text' value='Hello World' id='author_post_1_title' />",
       output_buffer
   end
 
@@ -1882,10 +1910,10 @@ def test_form_with_and_fields
     end
 
     expected = whole_form("/posts/123", "create-post", method: "patch") do
-      "<input name='post[title]' type='text' value='Hello World' />" \
-      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />" \
+      "<textarea name='post[body]' id='post_body' >\nBack to the hill and over it again!</textarea>" \
       "<input name='parent_post[secret]' type='hidden' value='0' />" \
-      "<input name='parent_post[secret]' checked='checked' type='checkbox' value='1' />"
+      "<input name='parent_post[secret]' checked='checked' type='checkbox' value='1' id='parent_post_secret' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1902,9 +1930,9 @@ def test_form_with_and_fields_with_object
     end
 
     expected = whole_form("/posts/123", "create-post", method: "patch") do
-      "<input name='post[title]' type='text' value='Hello World' />" \
-      "<textarea name='post[body]'>\nBack to the hill and over it again!</textarea>" \
-      "<input name='post[comment][name]' type='text' value='new comment' />"
+      "<input name='post[title]' type='text' value='Hello World' id='post_title' />" \
+      "<textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea>" \
+      "<input name='post[comment][name]' type='text' value='new comment' id='post_comment_name' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1918,7 +1946,7 @@ def test_form_with_and_fields_with_non_nested_association_and_without_object
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<input name='post[category][name]' type='text' />"
+      "<input name='post[category][name]' type='text' id='post_category_name' />"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1942,9 +1970,9 @@ def test_form_with_with_labelled_builder
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' /><br/>" \
-      "<label for='body'>Body:</label> <textarea name='post[body]'>\nBack to the hill and over it again!</textarea><br/>" \
-      "<label for='secret'>Secret:</label> <input name='post[secret]' type='hidden' value='0' /><input name='post[secret]' checked='checked' type='checkbox' value='1' /><br/>"
+      "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' id='post_title'/><br/>" \
+      "<label for='body'>Body:</label> <textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea><br/>" \
+      "<label for='secret'>Secret:</label> <input name='post[secret]' type='hidden' value='0' /><input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret' /><br/>"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1961,9 +1989,9 @@ def test_default_form_builder
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' /><br/>" \
-      "<label for='body'>Body:</label> <textarea name='post[body]'>\nBack to the hill and over it again!</textarea><br/>" \
-      "<label for='secret'>Secret:</label> <input name='post[secret]' type='hidden' value='0' /><input name='post[secret]' checked='checked' type='checkbox' value='1' /><br/>"
+      "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' id='post_title' /><br/>" \
+      "<label for='body'>Body:</label> <textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea><br/>" \
+      "<label for='secret'>Secret:</label> <input name='post[secret]' type='hidden' value='0' /><input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret' /><br/>"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1980,7 +2008,7 @@ def test_lazy_loading_default_form_builder
     end
 
     expected = whole_form("/posts/123", method: "patch") do
-      "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' /><br/>"
+      "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' id='post_title' /><br/>"
     end
 
     assert_dom_equal expected, output_buffer
@@ -1995,7 +2023,7 @@ def test_form_builder_override
       concat f.text_field(:title)
     end
 
-    expected = "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' /><br/>"
+    expected = "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' id='post_title' /><br/>"
 
     assert_dom_equal expected, output_buffer
   end
@@ -2007,7 +2035,7 @@ def test_lazy_loading_form_builder_override
       concat f.text_field(:title)
     end
 
-    expected = "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' /><br/>"
+    expected = "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' id='post_title' /><br/>"
 
     assert_dom_equal expected, output_buffer
   end
@@ -2020,9 +2048,9 @@ def test_fields_with_labelled_builder
     end
 
     expected =
-      "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' /><br/>" \
-      "<label for='body'>Body:</label> <textarea name='post[body]'>\nBack to the hill and over it again!</textarea><br/>" \
-      "<label for='secret'>Secret:</label> <input name='post[secret]' type='hidden' value='0' /><input name='post[secret]' checked='checked' type='checkbox' value='1' /><br/>"
+      "<label for='title'>Title:</label> <input name='post[title]' type='text' value='Hello World' id='post_title'/><br/>" \
+      "<label for='body'>Body:</label> <textarea name='post[body]' id='post_body'>\nBack to the hill and over it again!</textarea><br/>" \
+      "<label for='secret'>Secret:</label> <input name='post[secret]' type='hidden' value='0' /><input name='post[secret]' checked='checked' type='checkbox' value='1' id='post_secret' /><br/>"
 
     assert_dom_equal expected, output_buffer
   end

guides/source/configuring.md

@@ -578,6 +578,8 @@ Defaults to `'signed cookie'`.
 
 * `config.action_view.form_with_generates_remote_forms` determines whether `form_with` generates remote forms or not. This defaults to `true`.
 
+* `config.action_view.form_with_generates_ids` determines whether `form_with` generates ids on inputs. This defaults to `true`.
+
 ### Configuring Action Mailer
 
 There are a number of settings available on `config.action_mailer`:

railties/lib/rails/application/configuration.rb

@@ -81,6 +81,7 @@ def load_defaults(target_version)
 
           if respond_to?(:action_view)
             action_view.form_with_generates_remote_forms = true
+            action_view.form_with_generates_ids = true
           end
 
         when "5.2"

railties/test/application/configuration_test.rb

@@ -757,6 +757,68 @@ def index
       assert_match(/label/, last_response.body)
     end
 
+    test "form_with can be configured with form_with_generates_ids" do
+      app_file "config/initializers/form_builder.rb", <<-RUBY
+      Rails.configuration.action_view.form_with_generates_ids = false
+      RUBY
+
+      app_file "app/models/post.rb", <<-RUBY
+      class Post
+        include ActiveModel::Model
+        attr_accessor :name
+      end
+      RUBY
+
+      app_file "app/controllers/posts_controller.rb", <<-RUBY
+      class PostsController < ApplicationController
+        def index
+          render inline: "<%= begin; form_with(model: Post.new) {|f| f.text_field(:name)}; rescue => e; e.to_s; end %>"
+        end
+      end
+      RUBY
+
+      add_to_config <<-RUBY
+        routes.prepend do
+          resources :posts
+        end
+      RUBY
+
+      app "development"
+
+      get "/posts"
+
+      assert_no_match(/id=('|")post_name('|")/, last_response.body)
+    end
+
+    test "form_with outputs ids by default" do
+      app_file "app/models/post.rb", <<-RUBY
+      class Post
+        include ActiveModel::Model
+        attr_accessor :name
+      end
+      RUBY
+
+      app_file "app/controllers/posts_controller.rb", <<-RUBY
+      class PostsController < ApplicationController
+        def index
+          render inline: "<%= begin; form_with(model: Post.new) {|f| f.text_field(:name)}; rescue => e; e.to_s; end %>"
+        end
+      end
+      RUBY
+
+      add_to_config <<-RUBY
+        routes.prepend do
+          resources :posts
+        end
+      RUBY
+
+      app "development"
+
+      get "/posts"
+
+      assert_match(/id=('|")post_name('|")/, last_response.body)
+    end
+
     test "form_with can be configured with form_with_generates_remote_forms" do
       app_file "config/initializers/form_builder.rb", <<-RUBY
       Rails.configuration.action_view.form_with_generates_remote_forms = false