Extract BC3's rich_text_field helper

app/helpers/active_text/tag_helper.rb

@@ -0,0 +1,46 @@
+module ActiveText
+  module TagHelper
+    cattr_accessor(:id, instance_accessor: false) { 0 }
+
+    def active_text_field_tag(name, value = nil, options = {})
+      options = options.symbolize_keys
+      options[:input] ||= "trix_input_#{ActiveText::TagHelper.id += 1}"
+
+      editor_tag = content_tag("trix-editor", "", options)
+      input_tag = hidden_field_tag(name, value, id: options[:input])
+
+      editor_tag + input_tag
+    end
+  end
+end
+
+module ActionView::Helpers
+  class Tags::ActiveText < Tags::Base
+    include ActiveText::TagHelper
+
+    delegate :dom_id, to: ActionView::RecordIdentifier
+
+    def render
+      options = @options.stringify_keys
+      add_default_name_and_id(options)
+      options["input"] ||= dom_id(object, [options["id"], :trix_input].compact.join("_"))
+      active_text_field_tag(options.delete("name"), editable_value, options)
+    end
+
+    def editable_value
+      value.try(:to_trix_html)
+    end
+  end
+
+  module FormHelper
+    def active_text_field(object_name, method, options = {})
+      Tags::ActiveText.new(object_name, method, self, options).render
+    end
+  end
+
+  class FormBuilder
+    def active_text_field(method, options = {})
+      @template.active_text_field(@object_name, method, objectify_options(options))
+    end
+  end
+end

lib/active_text/engine.rb

@@ -10,5 +10,13 @@ module ActiveText
         include ActiveText::Attribute
       end
     end
+
+    # FIXME: Aren't helpers supposed to load automatically?
+    # https://github.com/rails/rails/issues/26627 ?
+    initializer "active_text.helper" do
+      ActiveSupport.on_load(:action_controller_base) do
+        helper ActiveText::TagHelper
+      end
+    end
   end
 end

test/dummy/app/views/messages/_form.html.erb

@@ -18,7 +18,7 @@
 
   <div class="field">
     <%= form.label :content %>
-    <%= form.text_area :content %>
+    <%= form.active_text_field :content %>
   </div>
 
   <div class="actions">