From 94e653af086695a6bce587ae7530ee0d134223bc Mon Sep 17 00:00:00 2001
From: Natalie Tay <natalie.tay@gmail.com>
Date: Wed, 21 May 2025 17:49:27 +0800
Subject: [PATCH] FEATURE: Also localize topic excerpts (#32839)

Currently, topic excerpts are not localized.

This commit adds the excerpt column into topic_localization and displays the
localized excerpt if present.
---
 app/models/topic_localization.rb              |  1 +
 app/serializers/listable_topic_serializer.rb  |  8 ++++-
 ...53324_add_excerpt_to_topic_localization.rb |  7 ++++
 .../listable_topic_serializer_spec.rb         | 33 +++++++++++++++++--
 4 files changed, 46 insertions(+), 3 deletions(-)
 create mode 100644 db/migrate/20250521053324_add_excerpt_to_topic_localization.rb

diff --git a/app/models/topic_localization.rb b/app/models/topic_localization.rb
index 5377fc6a2cf..3429886d67f 100644
--- a/app/models/topic_localization.rb
+++ b/app/models/topic_localization.rb
@@ -22,6 +22,7 @@ end
 #  localizer_user_id :integer          not null
 #  created_at        :datetime         not null
 #  updated_at        :datetime         not null
+#  excerpt           :string
 #
 # Indexes
 #
diff --git a/app/serializers/listable_topic_serializer.rb b/app/serializers/listable_topic_serializer.rb
index 8dfd5fb3d79..9e1db59ea51 100644
--- a/app/serializers/listable_topic_serializer.rb
+++ b/app/serializers/listable_topic_serializer.rb
@@ -111,7 +111,13 @@ class ListableTopicSerializer < BasicTopicSerializer
   end
 
   def excerpt
-    object.excerpt
+    e = object.excerpt
+
+    if (ContentLocalization.show_translated_topic?(object, scope))
+      object.get_localization&.excerpt.presence || e
+    else
+      e
+    end
   end
 
   alias include_last_read_post_number? has_user_data
diff --git a/db/migrate/20250521053324_add_excerpt_to_topic_localization.rb b/db/migrate/20250521053324_add_excerpt_to_topic_localization.rb
new file mode 100644
index 00000000000..35fb19db37a
--- /dev/null
+++ b/db/migrate/20250521053324_add_excerpt_to_topic_localization.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddExcerptToTopicLocalization < ActiveRecord::Migration[7.2]
+  def change
+    add_column :topic_localizations, :excerpt, :string, null: true, default: nil
+  end
+end
diff --git a/spec/serializers/listable_topic_serializer_spec.rb b/spec/serializers/listable_topic_serializer_spec.rb
index 92d3edb050b..31e63f78e42 100644
--- a/spec/serializers/listable_topic_serializer_spec.rb
+++ b/spec/serializers/listable_topic_serializer_spec.rb
@@ -1,9 +1,12 @@
 # frozen_string_literal: true
-RSpec.describe ListableTopicSerializer do
+
+describe ListableTopicSerializer do
   fab!(:topic)
 
   describe "#excerpt" do
-    it "can be extended by theme modifiers" do
+    before { topic.update!(excerpt: "This is excerrrpt-ional") }
+
+    it "can be included by theme modifiers" do
       payload = TopicListItemSerializer.new(topic, scope: Guardian.new, root: false).as_json
 
       expect(payload[:excerpt]).to eq(nil)
@@ -24,5 +27,31 @@ RSpec.describe ListableTopicSerializer do
 
       expect(payload[:excerpt]).to eq(topic.excerpt)
     end
+
+    it "does not include the excerpt by default" do
+      json = ListableTopicSerializer.new(topic, scope: Guardian.new).as_json
+
+      expect(json[:listable_topic][:excerpt]).to eq(nil)
+    end
+
+    it "returns the topic's excerpt" do
+      SiteSetting.always_include_topic_excerpts = true
+      json = ListableTopicSerializer.new(topic, scope: Guardian.new).as_json
+
+      expect(json[:listable_topic][:excerpt]).to eq("This is excerrrpt-ional")
+    end
+
+    it "returns the localized excerpt when setting is enabled" do
+      I18n.locale = "ja"
+      topic.update!(locale: "en")
+      Fabricate(:topic_localization, topic:, excerpt: "X", locale: "ja")
+
+      SiteSetting.experimental_content_localization = true
+      SiteSetting.always_include_topic_excerpts = true
+
+      json = ListableTopicSerializer.new(topic, scope: Guardian.new).as_json
+
+      expect(json[:listable_topic][:excerpt]).to eq("X")
+    end
   end
 end