From 1197750e7df1ba02da5005e6b0025cc1a0e11d08 Mon Sep 17 00:00:00 2001
From: Guo Xiang Tan <tgx_world@hotmail.com>
Date: Tue, 1 Aug 2017 17:26:03 +0900
Subject: [PATCH] PERF: Allow plugins to preload custom fields for topics in
 `CategoryList`.

---
 app/models/category_list.rb | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/app/models/category_list.rb b/app/models/category_list.rb
index ddf9ab5880b..6e98f9bc0a8 100644
--- a/app/models/category_list.rb
+++ b/app/models/category_list.rb
@@ -3,6 +3,9 @@ require_dependency 'pinned_check'
 class CategoryList
   include ActiveModel::Serialization
 
+  cattr_accessor :preloaded_topic_custom_fields
+  self.preloaded_topic_custom_fields = Set.new
+
   attr_accessor :categories,
                 :uncategorized,
                 :draft,
@@ -20,6 +23,13 @@ class CategoryList
     find_user_data
     sort_unpinned
     trim_results
+
+    if preloaded_topic_custom_fields.present?
+      Topic.preload_custom_fields(
+        @categories.map(&:displayable_topics).flatten,
+        preloaded_topic_custom_fields
+      )
+    end
   end
 
   def preload_key