Load groups hierarchy from data in DB

app/models/group.rb

@@ -7,5 +7,7 @@ class Group < ApplicationRecord
   has_many :children, class_name: 'Group', foreign_key: 'parent_id'
   belongs_to :parent, class_name: 'Group', optional: true
 
+  scope :roots, -> { where(parent_id: nil) }
+
   has_many :guests
 end

app/services/affinity_groups_hierarchy.rb

@@ -6,6 +6,12 @@ class AffinityGroupsHierarchy < Array
   def initialize
     super
     @references = {}
+
+    Group.roots.each do |group|
+      self << group.id
+
+      hydrate(group)
+    end
   end
 
   def find(name)
@@ -26,4 +32,14 @@ class AffinityGroupsHierarchy < Array
 
     @references[name_a].distance_to_common_ancestor(@references[name_b])
   end
+
+  private
+
+  def hydrate(group)
+    group.children.each do |child|
+      register_child(group.id, child.id)
+
+      hydrate(child)
+    end
+  end
 end

config/initializers/affinity_groups.rb

@@ -1,41 +0,0 @@
-# Copyright (C) 2024 Manuel Bustillo
-
-require_relative '../../app/services/affinity_groups_hierarchy'
-
-hierarchy = AffinityGroupsHierarchy.instance
-
-hierarchy << 'guests_a'
-hierarchy << 'guests_b'
-hierarchy << 'common_guests'
-
-hierarchy.register_child('guests_a', 'family_a')
-hierarchy.register_child('family_a', 'close_family_a')
-hierarchy.register_child('family_a', 'cousins_a')
-hierarchy.register_child('family_a', 'relatives_a')
-
-hierarchy.register_child('guests_a', 'work_a')
-hierarchy.register_child('work_a', 'besties_work_a')
-
-hierarchy.register_child('guests_a', 'friends_a')
-hierarchy.register_child('friends_a', 'college_friends_a')
-hierarchy.register_child('friends_a', 'high_school_friends_a')
-hierarchy.register_child('friends_a', 'childhood_friends_a')
-
-hierarchy.register_child('guests_a', 'sports_a')
-hierarchy.register_child('sports_a', 'basket_team_a')
-hierarchy.register_child('sports_a', 'football_team_a')
-
-hierarchy.register_child('guests_b', 'family_b')
-hierarchy.register_child('family_b', 'close_family_b')
-hierarchy.register_child('family_b', 'cousins_b')
-hierarchy.register_child('family_b', 'relatives_b')
-
-hierarchy.register_child('guests_b', 'work_b')
-hierarchy.register_child('work_b', 'besties_work_b')
-
-hierarchy.register_child('guests_b', 'friends_b')
-hierarchy.register_child('friends_b', 'college_friends_b')
-hierarchy.register_child('friends_b', 'high_school_friends_b')
-hierarchy.register_child('friends_b', 'childhood_friends_b')
-
-hierarchy.register_child('common_guests', 'dance_club')