FEATURE: add option to sort topic query result via plugin. (#25349)

Previously, it was not possible to modify the sorting order of the `TopicQuery` result from a plugin. This feature adds support to specify custom sorting functionality in a plugin. We're using the `apply_modifier` method in the `DiscoursePluginRegistry` module to achieve it.

Co-authored-by: Alan Guo Xiang Tan <gxtan1990@gmail.com>

app/assets/javascripts/discourse/app/raw-views/topic-list-header-column.js

@@ -18,13 +18,18 @@ export default EmberObject.extend({
 
   @discourseComputed
   sortIcon() {
-    const asc = this.parent.ascending ? "up" : "down";
+    const isAscending = this.parent.ascending || this.parent.context?.ascending;
+    const asc = isAscending ? "up" : "down";
     return `chevron-${asc}`;
   },
 
   @discourseComputed
   isSorting() {
-    return this.sortable && this.parent.order === this.order;
+    return (
+      this.sortable &&
+      (this.parent.order === this.order ||
+        this.parent.context?.order === this.order)
+    );
   },
 
   @discourseComputed

lib/topic_query.rb

@@ -664,9 +664,21 @@ class TopicQuery
   end
 
   def apply_ordering(result, options = {})
-    sort_column = SORTABLE_MAPPING[options[:order]] || "default"
+    order_option = options[:order]
     sort_dir = (options[:ascending] == "true") ? "ASC" : "DESC"
 
+    new_result =
+      DiscoursePluginRegistry.apply_modifier(
+        :topic_query_apply_ordering_result,
+        result,
+        order_option,
+        sort_dir,
+        options,
+        self,
+      )
+    return new_result if !new_result.nil? && new_result != result
+    sort_column = SORTABLE_MAPPING[order_option] || "default"
+
     # If we are sorting in the default order desc, we should consider including pinned
     # topics. Otherwise, just use bumped_at.
     if sort_column == "default"

spec/lib/topic_query_spec.rb

@@ -2091,6 +2091,40 @@ RSpec.describe TopicQuery do
     end
   end
 
+  describe "#apply_ordering" do
+    fab!(:topic1) { Fabricate(:topic, spam_count: 3, bumped_at: 3.hours.ago) }
+    fab!(:topic2) { Fabricate(:topic, spam_count: 2, bumped_at: 3.minutes.ago) }
+    fab!(:topic3) { Fabricate(:topic, spam_count: 3, bumped_at: 1.hour.ago) }
+
+    let(:modifier_block) do
+      Proc.new do |result, sort_column, sort_dir, options, topic_query|
+        if sort_column == "spam"
+          sort_column = "spam_count"
+          result.order("topics.#{sort_column} #{sort_dir}, bumped_at DESC")
+        end
+      end
+    end
+
+    it "returns the result of topic_query_apply_ordering_result modifier" do
+      plugin_instance = Plugin::Instance.new
+      plugin_instance.register_modifier(:topic_query_apply_ordering_result, &modifier_block)
+
+      topics = TopicQuery.new(nil, order: "spam", ascending: "false").list_latest.topics
+      expect(topics.map(&:id)).to eq([topic3.id, topic1.id, topic2.id])
+    ensure
+      DiscoursePluginRegistry.unregister_modifier(
+        plugin_instance,
+        :topic_query_apply_ordering_result,
+        &modifier_block
+      )
+    end
+
+    it "ignores the result of topic_query_apply_ordering_result if modifier not registered" do
+      topics = TopicQuery.new(nil, order: "spam", ascending: "false").list_latest.topics
+      expect(topics.map(&:id)).to eq([topic2.id, topic3.id, topic1.id])
+    end
+  end
+
   describe "show_category_definitions_in_topic_lists setting" do
     fab!(:category) { Fabricate(:category_with_definition) }
     fab!(:subcategory) { Fabricate(:category_with_definition, parent_category: category) }