FIX: n+1 in search result (#438)

When assignment data is preloaded, cache variable should be set when topic is assigned but also when topic is not assigned to avoid additional queries.

plugin.rb

@@ -306,10 +306,9 @@ after_initialize do
             topic_assignments&.find { |assignment| assignment.target_type == "Topic" }
           indirect_assignments =
             topic_assignments&.select { |assignment| assignment.target_type == "Post" }
-          if direct_assignment
+
-            assigned_to = direct_assignment.assigned_to
+          post.topic.preload_assigned_to(direct_assignment&.assigned_to)
-            post.topic.preload_assigned_to(assigned_to)
+          post.topic.preload_indirectly_assigned_to(nil)
-          end
           if indirect_assignments.present?
             indirect_assignment_map =
               indirect_assignments.reduce({}) do |acc, assignment|

spec/requests/search_controller_spec.rb

@@ -37,4 +37,21 @@ describe SearchController do
     expect(assigned_to_group_data["assign_icon"]).to eq("group-plus")
     expect(assigned_to_group_data["assign_path"]).to eq("/g/#{group.name}/assigned/everyone")
   end
+
+  it "does not result in N+1 queries when search returns multiple results" do
+    SearchIndexer.enable
+    SiteSetting.assigns_public = true
+    post = Fabricate(:post, topic: Fabricate(:topic, title: "this is an awesome title"))
+
+    get "/search/query.json", params: { term: "awesome" }
+
+    initial_sql_queries_count =
+      track_sql_queries { get "/search/query.json", params: { term: "awesome" } }.count
+
+    Fabricate(:post, topic: Fabricate(:topic, title: "this is an awesome title 2"))
+    Fabricate(:post, topic: Fabricate(:topic, title: "this is an awesome title 3"))
+    new_sql_queries_count =
+      track_sql_queries { get "/search/query.json", params: { term: "awesome" } }.count
+    expect(new_sql_queries_count).to eq(initial_sql_queries_count)
+  end
 end