DEV: Category#with_ancestor_ids

app/models/category.rb

@@ -262,6 +262,37 @@ def self.preload_user_fields!(guardian, categories)
  end
  end
 
+ def self.with_ancestor_ids
+ categories =
+ select(
+ "categories.id",
+ "ARRAY[]::integer[] AS ancestor_ids",
+ "categories.parent_category_id AS ancestor_id",
+ )
+
+ (SiteSetting.max_category_nesting - 2).times do
+ categories =
+ Category.from("(#{categories.to_sql}) AS category_ancestors").select(
+ "category_ancestors.id",
+ "category_ancestors.ancestor_id || category_ancestors.ancestor_ids AS ancestor_ids",
+ "(SELECT c.parent_category_id FROM categories c WHERE c.id = category_ancestors.ancestor_id) AS ancestor_id",
+ )
+ end
+
+ categories =
+ Category.from("(#{categories.to_sql}) AS category_ancestors").select(
+ "category_ancestors.id",
+ "(SELECT array_remove(category_ancestors.ancestor_id || category_ancestors.ancestor_ids, NULL)) AS ancestor_ids",
+ )
+
+ categories =
+ Category.joins(
+ "INNER JOIN (#{categories.to_sql}) AS category_ancestors ON categories.id = category_ancestors.id",
+ ).select("categories.*", "category_ancestors.ancestor_ids")
+
+ Category.from("(#{categories.to_sql}) AS categories")
+ end
+
  def self.ancestors_of(category_ids)
  ancestor_ids = []