📦 closure_tree/ ClosureTree

Installation

Note that closure_tree only supports ActiveRecord 7.2 and later, and has test coverage for MySQL, PostgreSQL, and SQLite.

1. Add gem 'closure_tree' to your Gemfile

2. Run bundle install

3. Add has_closure_tree (or acts_as_tree, which is an alias of the same method) to your hierarchical model:

   class Tag < ApplicationRecord
     has_closure_tree
   end
   
   class AnotherTag < ApplicationRecord
     acts_as_tree
   end
   

   Make sure you check out the large number of options that has_closure_tree accepts.

   Note: The acts_as_tree alias is only created if your model doesn't already have a method with that name. This prevents conflicts with other gems like the original acts_as_tree gem.

   IMPORTANT: Make sure you add has_closure_tree after attr_accessible and self.table_name = lines in your model.

   If you're already using other hierarchical gems, like ancestry or acts_as_tree, please refer to the warning section!

4. Add a migration to add a parent_id column to the hierarchical model. You may want to also add a column for deterministic ordering of children, but that's optional.

   class AddParentIdToTag < ActiveRecord::Migration[7.2]
     def change
       add_column :tags, :parent_id, :integer
     end
   end
   

   The column must be nullable. Root nodes have a NULL parent_id.

5. Run rails g closure_tree:migration tag (and replace tag with your model name) to create the closure tree table for your model.

…

Run with PostgreSQL

DATABASE_URL=postgres://localhost/closure_tree_test rake test

Run with MySQL

DATABASE_URL=mysql2://localhost/closure_tree_test rake test