FIX: Update category breadcrumbs more reliably (#26608)

The breadcrumbs were updated everytime there were changes to the
categories which was not efficient and caused unnecessary rerendering
of the CategoryDrop elements when "lazy load categories" is enabled.

This commit also ensures that all category fields are serialized for
ancestors too for the categories#search endpoint.

app/assets/javascripts/discourse/app/components/bread-crumbs.js

@@ -10,30 +10,31 @@ export default Component.extend({
   editingCategory: false,
   editingCategoryTab: null,
 
-  @discourseComputed("category.ancestors", "categories", "noSubcategories")
-  categoryBreadcrumbs(categoryAncestors, filteredCategories, noSubcategories) {
-    categoryAncestors = categoryAncestors || [];
-    const parentCategories = [undefined, ...categoryAncestors];
-    const categories = [...categoryAncestors, undefined];
-    const zipped = parentCategories.map((x, i) => [x, categories[i]]);
+  @discourseComputed("category", "categories", "noSubcategories")
+  categoryBreadcrumbs(category, filteredCategories, noSubcategories) {
+    const ancestors = category?.ancestors || [];
+    const parentCategories = [undefined, ...ancestors];
+    const categories = [...ancestors, undefined];
 
-    return zipped.map((record) => {
-      const [parentCategory, category] = record;
+    return parentCategories
+      .map((x, i) => [x, categories[i]])
+      .map((record) => {
+        const [parentCategory, subCategory] = record;
 
-      const options = filteredCategories.filter(
-        (c) =>
-          c.get("parentCategory.id") === (parentCategory && parentCategory.id)
-      );
+        const options = filteredCategories.filter(
+          (c) =>
+            c.get("parentCategory.id") === (parentCategory && parentCategory.id)
+        );
 
-      return {
-        category,
-        parentCategory,
-        options,
-        isSubcategory: !!parentCategory,
-        noSubcategories: !category && noSubcategories,
-        hasOptions: !parentCategory || parentCategory.has_children,
-      };
-    });
+        return {
+          category: subCategory,
+          parentCategory,
+          options,
+          isSubcategory: !!parentCategory,
+          noSubcategories: !subCategory && noSubcategories,
+          hasOptions: !parentCategory || parentCategory.has_children,
+        };
+      });
   },
 
   @discourseComputed("siteSettings.tagging_enabled", "editingCategory")

app/controllers/categories_controller.rb

@@ -436,6 +436,7 @@ class CategoriesController < ApplicationController
 
     if include_ancestors
       ancestors = Category.secured(guardian).ancestors_of(categories.map(&:id))
+      Category.preload_user_fields!(guardian, ancestors)
       response[:ancestors] = serialize_data(ancestors, SiteCategorySerializer, scope: guardian)
     end