Merge pull request rails#51746 from 3v0k4/hidden-form

Use the given `form` in `html_options` for the hidden field in `collection_check_boxes`

Author: rafaelfranca

actionview/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   Respect `html_options[:form]` when `collection_checkboxes` generates the
+    hidden `<input>`.
+
+    *Riccardo Odone*
+
 *   Layouts have access to local variables passed to `render`.
 
     This fixes #31680 which was a regression in Rails 5.1.

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

@@ -106,7 +106,8 @@ def render_collection_for(builder_class, &block)
 
           def hidden_field
             hidden_name = @html_options[:name] || hidden_field_name
-            @template_object.hidden_field_tag(hidden_name, "", id: nil)
+            options = { id: nil, form: @html_options[:form] }
+            @template_object.hidden_field_tag(hidden_name, "", options)
           end
 
           def hidden_field_name

actionview/test/template/form_collections_helper_test.rb

@@ -272,6 +272,13 @@ def with_collection_checkboxes(*args, &block)
     assert_select "input[type=hidden][name='user[other_category_ids][]'][value=''][autocomplete='off']", count: 1
   end
 
+  test "collection check boxes generates a hidden field using the given :form in :html_options" do
+    collection = [Category.new(1, "Category 1"), Category.new(2, "Category 2")]
+    with_collection_checkboxes :user, :category_ids, collection, :id, :name, {}, { form: "my_form" }
+
+    assert_select "input[type=hidden][value=''][autocomplete='off'][form='my_form']", count: 1
+  end
+
   test "collection check boxes generates a hidden field with index if it was provided" do
     collection = [Category.new(1, "Category 1"), Category.new(2, "Category 2")]
     with_collection_checkboxes :user, :category_ids, collection, :id, :name, index: 322