DEV: No longer preload categories (#24950)

Categories will no longer be preloaded when `lazy_load_categories` is
enabled through PreloadStore.

Instead, the list of site categories will continue to be populated
by `Site.updateCategory` as more and more categories are being loaded
from different sources (topic lists, category selectors, etc).

app/assets/javascripts/discourse/app/instance-initializers/category-badge-css-generator.js

@@ -9,7 +9,7 @@ export default {
     this.site = owner.lookup("service:site");
 
     // If the site is login_required and the user is anon there will be no categories preloaded.
-    if (!this.site.categories) {
+    if (!this.site.categories?.length) {
       return;
     }
 

app/assets/javascripts/discourse/app/instance-initializers/category-color-css-generator.js

@@ -12,7 +12,7 @@ export default {
     this.site = owner.lookup("service:site");
 
     // If the site is login_required and the user is anon there will be no categories preloaded.
-    if (!this.site.categories) {
+    if (!this.site.categories?.length) {
       return;
     }
 

app/assets/javascripts/discourse/app/instance-initializers/hashtag-css-generator.js

@@ -18,7 +18,7 @@ export default {
     // If the site is login_required and the user is anon there will be no categories
     // preloaded, so there will be no category color CSS variables generated by
     // the category-color-css-generator initializer.
-    if (!this.site.categories) {
+    if (!this.site.categories?.length) {
       return;
     }
 

app/assets/javascripts/discourse/app/models/site.js

@@ -20,6 +20,7 @@ const Site = RestModel.extend({
     this._super(...arguments);
 
     this.topicCountDesc = ["topic_count:desc"];
+    this.categories = this.categories || [];
   },
 
   @discourseComputed("notification_types")

app/models/site.rb

@@ -4,9 +4,6 @@
 class Site
   include ActiveModel::Serialization
 
-  # Number of categories preloaded when lazy_load_categories is enabled
-  LAZY_LOAD_CATEGORIES_LIMIT = 10
-
   cattr_accessor :preloaded_category_custom_fields
 
   def self.reset_preloaded_category_custom_fields
@@ -157,13 +154,9 @@ class Site
 
         self.class.categories_callbacks.each { |callback| callback.call(categories, @guardian) }
 
-        if SiteSetting.lazy_load_categories
-          categories[0...Site::LAZY_LOAD_CATEGORIES_LIMIT]
-        else
         categories
       end
   end
-  end
 
   def groups
     query =

app/serializers/site_serializer.rb

@@ -238,6 +238,10 @@ class SiteSerializer < ApplicationSerializer
     object.categories.map { |c| c.to_h }
   end
 
+  def include_categories?
+    !SiteSetting.lazy_load_categories
+  end
+
   def markdown_additional_options
     Site.markdown_additional_options
   end

spec/models/site_spec.rb

@@ -183,17 +183,6 @@ RSpec.describe Site do
         DiscoursePluginRegistry.clear_modifiers!
       end
     end
-
-    context "when lazy_load_categories" do
-      before { SiteSetting.lazy_load_categories = true }
-
-      it "limits the number of categories" do
-        stub_const(Site, "LAZY_LOAD_CATEGORIES_LIMIT", 1) do
-          categories = Site.new(Guardian.new).categories
-          expect(categories.size).to eq(1)
-        end
-      end
-    end
   end
 
   it "omits groups user can not see" do

spec/serializers/site_serializer_spec.rb

@@ -131,6 +131,14 @@ RSpec.describe SiteSerializer do
     expect(serialized[:shared_drafts_category_id]).to eq(nil)
   end
 
+  it "does not include categories if lazy_load_categories" do
+    SiteSetting.lazy_load_categories = true
+
+    serialized = described_class.new(Site.new(guardian), scope: guardian, root: false).as_json
+
+    expect(serialized[:categories]).to eq(nil)
+  end
+
   describe "#anonymous_default_navigation_menu_tags" do
     fab!(:user)
     fab!(:tag) { Fabricate(:tag, name: "dev", description: "some description") }