Fix updating rich text via nested attributes

Closes rails#35159.

actiontext/lib/action_text/attribute.rb

@@ -34,14 +34,11 @@ def #{name}=(body)
           end
         CODE
 
-        has_one :"rich_text_#{name}", -> { where(name: name) }, class_name: "ActionText::RichText", as: :record, inverse_of: :record, dependent: :destroy
+        has_one :"rich_text_#{name}", -> { where(name: name) },
+          class_name: "ActionText::RichText", as: :record, inverse_of: :record, autosave: true, dependent: :destroy
 
         scope :"with_rich_text_#{name}", -> { includes("rich_text_#{name}") }
         scope :"with_rich_text_#{name}_and_embeds", -> { includes("rich_text_#{name}": { embeds_attachments: :blob }) }
-
-        after_save do
-          public_send(name).save if public_send(name).changed?
-        end
       end
     end
   end

actiontext/test/dummy/app/models/message.rb

@@ -1,4 +1,7 @@
 class Message < ApplicationRecord
   has_rich_text :content
   has_rich_text :body
+
+  has_one :review
+  accepts_nested_attributes_for :review
 end

actiontext/test/dummy/app/models/review.rb

@@ -0,0 +1,5 @@
+class Review < ApplicationRecord
+  belongs_to :message
+
+  has_rich_text :content
+end

actiontext/test/dummy/db/migrate/20190317200724_create_reviews.rb

@@ -0,0 +1,8 @@
+class CreateReviews < ActiveRecord::Migration[6.0]
+  def change
+    create_table :reviews do |t|
+      t.belongs_to :message, null: false
+      t.string :author_name, null: false
+    end
+  end
+end

actiontext/test/dummy/db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2019_03_05_172303) do
+ActiveRecord::Schema.define(version: 2019_03_17_200724) do
 
   create_table "action_text_rich_texts", force: :cascade do |t|
     t.string "name", null: false
@@ -61,5 +61,11 @@
     t.datetime "updated_at", precision: 6, null: false
   end
 
+  create_table "reviews", force: :cascade do |t|
+    t.integer "message_id", null: false
+    t.string "author_name", null: false
+    t.index ["message_id"], name: "index_reviews_on_message_id"
+  end
+
   add_foreign_key "active_storage_attachments", "active_storage_blobs", column: "blob_id"
 end

actiontext/test/unit/model_test.rb

@@ -49,8 +49,22 @@ class ActionText::ModelTest < ActiveSupport::TestCase
     assert_equal "Hello world", message.content.to_plain_text
   end
 
-  test "save body" do
+  test "saving body" do
     message = Message.create(subject: "Greetings", body: "<h1>Hello world</h1>")
     assert_equal "Hello world", message.body.to_plain_text
   end
+
+  test "saving content via nested attributes" do
+    message = Message.create! subject: "Greetings", content: "<h1>Hello world</h1>",
+      review_attributes: { author_name: "Marcia", content: "Nice work!" }
+    assert_equal "Nice work!", message.review.content.to_plain_text
+  end
+
+  test "updating content via nested attributes" do
+    message = Message.create! subject: "Greetings", content: "<h1>Hello world</h1>",
+      review_attributes: { author_name: "Marcia", content: "Nice work!" }
+
+    message.update! review_attributes: { id: message.review.id, content: "Great work!" }
+    assert_equal "Great work!", message.review.reload.content.to_plain_text
+  end
 end