add touch option to update ancestor timestamp

lib/parentry.rb

@@ -7,7 +7,7 @@ module Parentry
 
   def self.included(base)
     base.class_eval do
-      mattr_accessor :parentry_column, :depth_offset, :cache_depth
+      mattr_accessor :parentry_column, :depth_offset, :cache_depth, :touch_ancestors
 
       belongs_to :parent, class_name: base_class.name
       has_many :children, class_name: base_class.name, foreign_key: :parent_id, dependent: :destroy
@@ -25,6 +25,10 @@ def self.included(base)
       after_update :cascade_parentry, if: proc { changes[parentry_column].present? }
       after_save :cache_parentry_depth, if: proc { cache_depth && depth != parentry_depth }
 
+      after_save :touch_ancestors_callback
+      after_touch :touch_ancestors_callback
+      after_destroy :touch_ancestors_callback
+
       scope :order_by_parentry, -> { order("nlevel(#{parentry_column})") }
 
       scope :before_depth, ->(depth) { where("nlevel(#{parentry_column}) - 1 < ?", depth + depth_offset) }

lib/parentry/class_methods.rb

@@ -4,6 +4,7 @@ def parentry(options = {})
       self.parentry_column = options.fetch(:parentry_column, 'parentry')
       self.depth_offset = options.fetch(:depth_offset, 0)
       self.cache_depth = options.fetch(:cache_depth, false)
+      self.touch_ancestors = options.fetch(:touch, false)
     end
 
     def arrange(options = {})

lib/parentry/instance_methods.rb

@@ -5,8 +5,8 @@ def parentry_scope
     end
 
     def prevent_circular_parentry
-      computed = compute_parentry
-      errors.add(:parentry, 'contains a circular reference') unless computed.split('.').uniq == computed.split('.')
+      computed = parse_parentry(compute_parentry)
+      errors.add(:parentry, 'contains a circular reference') unless computed.uniq == computed
     end
 
     def commit_parentry
@@ -40,5 +40,33 @@ def compute_parentry
     def parentry
       read_attribute(parentry_column)
     end
+
+    def parse_parentry(input = parentry)
+      input.to_s.split('.').map(&:to_i)
+    end
+
+    def touch_ancestors_callback
+      return unless touch_ancestors
+      return if touch_callbacks_disabled?
+
+      parentry_scope.where(id: ancestor_ids_was + ancestor_ids).each do |ancestor|
+        ancestor.without_touch_callbacks { ancestor.touch }
+      end
+    end
+
+    def without_touch_callbacks
+      @disable_touch_callbacks = true
+      yield
+      @disable_touch_callbacks = false
+    end
+
+    def touch_callbacks_disabled?
+      @disable_touch_callbacks
+    end
+
+    def ancestor_ids_was
+      return [] unless changes[parentry_column]
+      parse_parentry(changes[parentry_column][0]).tap(&:pop)
+    end
   end
 end

lib/parentry/navigation.rb

@@ -13,7 +13,7 @@ def root?
     end
 
     def path_ids
-      parentry.split('.').map(&:to_i)
+      parse_parentry
     end
 
     def path(scopes = {})

spec/db/schema.rb

@@ -6,10 +6,21 @@
     t.ltree :parentry
     t.integer :parentry_depth
     t.integer :rank
+
+    t.timestamps null: false
   end
 
   create_table :one_depth_tree_nodes, force: true do |t|
     t.integer :parent_id
     t.ltree :parentry
+
+    t.timestamps null: false
+  end
+
+  create_table :touch_tree_nodes, force: true do |t|
+    t.integer :parent_id
+    t.ltree :parentry
+
+    t.timestamps null: false
   end
 end

spec/instance_methods_spec.rb

@@ -64,4 +64,55 @@
       expect(child.reload.parentry).to eq "#{node.parentry}.#{child.id}"
     end
   end
+
+  context 'touch ancestors option' do
+    context 'enabled' do
+      it 'should update ancestor timestamp' do
+        parent = TouchTreeNode.create
+        expect do
+          parent.children.create
+        end.to change { parent.reload.updated_at }
+      end
+
+      context 'parent changes' do
+        it 'should update old parent timestamp' do
+          parent = TouchTreeNode.create
+          node = parent.children.create
+          new_parent = TouchTreeNode.create
+
+          expect do
+            node.update_attributes(parent: new_parent)
+          end.to change { parent.reload.updated_at }
+        end
+
+        it 'should update new parent timestamp' do
+          parent = TouchTreeNode.create
+          node = parent.children.create
+          new_parent = TouchTreeNode.create
+
+          expect do
+            node.update_attributes(parent: new_parent)
+          end.to change { new_parent.reload.updated_at }
+        end
+      end
+
+      it 'should update parent timestamp when child is deleted' do
+        parent = TouchTreeNode.create
+        node = parent.children.create
+
+        expect do
+          node.destroy
+        end.to change { parent.reload.updated_at }
+      end
+    end
+
+    context 'disabled' do
+      it 'should not update ancestor timestamp' do
+        parent = TreeNode.create
+        expect do
+          parent.children.create
+        end.not_to change { parent.reload.updated_at }
+      end
+    end
+  end
 end

spec/support/models.rb

@@ -7,3 +7,8 @@ class OneDepthTreeNode < ActiveRecord::Base
   include Parentry
   parentry depth_offset: 1
 end
+
+class TouchTreeNode < ActiveRecord::Base
+  include Parentry
+  parentry touch: true
+end