FEATURE: Add setting to exclude groups from /about page (#28809)

This commit adds a new `about_page_hidden_groups` setting to exclude members of specific groups from the admin and moderator lists on the /about page.

Internal topic: t/137717.

app/models/about.rb

@@ -69,14 +69,17 @@ class About
   end
 
   def moderators
-    @moderators ||= User.where(moderator: true, admin: false).human_users.order("last_seen_at DESC")
+    @moderators ||=
+      apply_excluded_groups(
+        User.where(moderator: true, admin: false).human_users.order(last_seen_at: :desc),
+      )
   end
 
   def admins
     @admins ||=
       DiscoursePluginRegistry.apply_modifier(
         :about_admins,
-        User.where(admin: true).human_users.order("last_seen_at DESC"),
+        apply_excluded_groups(User.where(admin: true).human_users.order(last_seen_at: :desc)),
       )
   end
 
@@ -137,4 +140,18 @@ class About
   def category_mods_limit=(number)
     @category_mods_limit = number
   end
+
+  private
+
+  def apply_excluded_groups(query)
+    group_ids = SiteSetting.about_page_hidden_groups_map
+    return query if group_ids.blank?
+
+    query.joins(
+      DB.sql_fragment(
+        "LEFT JOIN group_users ON group_id IN (:group_ids) AND user_id = users.id",
+        group_ids:,
+      ),
+    ).where("group_users.id": nil)
+  end
 end

config/locales/server.en.yml

@@ -2709,6 +2709,7 @@ en:
 
     page_loading_indicator: "Configure the loading indicator which appears during page navigations within Discourse. 'Spinner' is a full page indicator. 'Slider' shows a narrow bar at the top of the screen."
     show_user_menu_avatars: "Show user avatars in the user menu"
+    about_page_hidden_groups: "Do not show members of specific groups on the /about page."
     view_raw_email_allowed_groups: "Groups which can view the raw email content of a post if it was created by an incoming email. This includes email headers and other technical information."
     experimental_flags_admin_page_enabled_groups: "EXPERIMENTAL: Remove the Moderation Flags link from the admin sidebar."
 

config/site_settings.yml

@@ -410,6 +410,9 @@ basic:
   show_user_menu_avatars:
     client: true
     default: false
+  about_page_hidden_groups:
+    default: ""
+    type: group_list
   extended_site_description:
     default: ""
     max: 10_000

spec/models/about_spec.rb

@@ -132,6 +132,29 @@ RSpec.describe About do
     end
   end
 
+  describe "#moderators" do
+    fab!(:mod_1) { Fabricate(:moderator) }
+    fab!(:mod_2) { Fabricate(:moderator) }
+    fab!(:mod_3) { Fabricate(:moderator) }
+
+    context "with the about_page_hidden_groups setting" do
+      fab!(:group_1) { Fabricate(:group, users: [mod_1, mod_3]) }
+      fab!(:group_2) { Fabricate(:group, users: [mod_3]) }
+      fab!(:group_3) { Fabricate(:group) }
+
+      before { SiteSetting.about_page_hidden_groups = [group_1.id, group_2.id].join("|") }
+
+      it "hides moderators that are in any of the specified groups" do
+        expect(About.new.moderators).to contain_exactly(mod_2)
+      end
+
+      it "doesn't hide any moderators if the setting is empty" do
+        SiteSetting.about_page_hidden_groups = ""
+        expect(About.new.moderators).to contain_exactly(mod_1, mod_2, mod_3)
+      end
+    end
+  end
+
   describe "#admins" do
     fab!(:admin_mark) { Fabricate(:admin, name: "mark") }
     fab!(:admin_matt) { Fabricate(:admin, name: "matt") }
@@ -148,5 +171,22 @@ RSpec.describe About do
         DiscoursePluginRegistry.unregister_modifier(plugin_instance, :about_admins, &modifier_block)
       end
     end
+
+    context "with the about_page_hidden_groups setting" do
+      fab!(:group_1) { Fabricate(:group, users: [admin_mark, admin_matt]) }
+      fab!(:group_2) { Fabricate(:group, users: [admin_mark]) }
+      fab!(:group_3) { Fabricate(:group, users: [admin_kate]) }
+
+      before { SiteSetting.about_page_hidden_groups = [group_1.id, group_2.id].join("|") }
+
+      it "hides admins that are in any of the specified groups" do
+        expect(About.new.admins).to contain_exactly(admin_kate)
+      end
+
+      it "doesn't hide any admins if the setting is empty" do
+        SiteSetting.about_page_hidden_groups = ""
+        expect(About.new.admins).to contain_exactly(admin_kate, admin_mark, admin_matt)
+      end
+    end
   end
 end