Add the :touch to update ancestors on save

README.rdoc

@@ -73,14 +73,17 @@ The has_ancestry methods supports the following options:
                          :destroy   All children are destroyed as well (default)
                          :rootify   The children of the destroyed node become root nodes
                          :restrict  An AncestryException is raised if any children exist
-                         :adopt     The orphan subtree is added to the parent of the deleted node.If the deleted node is Root, then rootify the orphan subtree.
+                         :adopt     The orphan subtree is added to the parent of the deleted node.
+                                    If the deleted node is Root, then rootify the orphan subtree.
   :cache_depth           Cache the depth of each node in the 'ancestry_depth' column (default: false)
                          If you turn depth_caching on for an existing model:
                          - Migrate: add_column [table], :ancestry_depth, :integer, :default => 0
                          - Build cache: TreeNode.rebuild_depth_cache!
   :depth_cache_column    Pass in a symbol to store depth cache in a different column
   :primary_key_format    Supply a regular expression that matches the format of your primary key.
                          By default, primary keys only match integers ([0-9]+).
+  :touch                 Instruct Ancestry to touch the ancestors of a node when it changes, to
+                         invalidate nested key-based caches. (default: false)
 
 = (Named) Scopes
 

lib/ancestry/has_ancestry.rb

@@ -3,7 +3,7 @@ def has_ancestry options = {}
     # Check options
     raise Ancestry::AncestryException.new("Options for has_ancestry must be in a hash.") unless options.is_a? Hash
     options.each do |key, value|
-      unless [:ancestry_column, :orphan_strategy, :cache_depth, :depth_cache_column].include? key
+      unless [:ancestry_column, :orphan_strategy, :cache_depth, :depth_cache_column, :touch].include? key
         raise Ancestry::AncestryException.new("Unknown option for has_ancestry: #{key.inspect} => #{value.inspect}.")
       end
     end
@@ -25,7 +25,11 @@ def has_ancestry options = {}
     # Save self as base class (for STI)
     cattr_accessor :ancestry_base_class
     self.ancestry_base_class = self
-
+
+    # Touch ancestors after updating
+    cattr_accessor :touch_ancestors
+    self.touch_ancestors = options[:touch] || false
+
     # Validate format of ancestry column value
     validates_format_of ancestry_column, :with => Ancestry::ANCESTRY_PATTERN, :allow_nil => true
 
@@ -69,6 +73,10 @@ def has_ancestry options = {}
         where("#{depth_cache_column} #{operator} ?", depth)
       }
     end
+
+    after_save :touch_ancestors_callback
+    after_touch :touch_ancestors_callback
+    after_destroy :touch_ancestors_callback
   end
 
   # Alias has_ancestry with acts_as_tree, if it's available.

lib/ancestry/instance_methods.rb

@@ -64,6 +64,25 @@ def apply_orphan_strategy
       end
     end
 
+    # Touch each of this record's ancestors
+    def touch_ancestors_callback
+
+      # Skip this if callbacks are disabled
+      unless ancestry_callbacks_disabled?
+
+        # Only touch if the option is enabled
+        if self.ancestry_base_class.touch_ancestors
+
+          # Touch each of the old *and* new ancestors
+          self.class.where(id: (ancestor_ids + ancestor_ids_was).uniq).each do |ancestor|
+            ancestor.without_ancestry_callbacks do
+              ancestor.touch
+            end
+          end
+        end
+      end
+    end
+
     # The ancestry value for this record's children
     def child_ancestry
       # New records cannot have children
@@ -77,16 +96,28 @@ def ancestry_changed?
       changed.include?(self.ancestry_base_class.ancestry_column.to_s)
     end
 
+    def parse_ancestry_column obj
+      obj.to_s.split('/').map { |id| cast_primary_key(id) }
+    end
+
     def ancestor_ids
-      read_attribute(self.ancestry_base_class.ancestry_column).to_s.split('/').map { |id| cast_primary_key(id) }
+      parse_ancestry_column(read_attribute(self.ancestry_base_class.ancestry_column))
     end
 
     def ancestor_conditions
       {primary_key_with_table => ancestor_ids}
     end
 
     def ancestors depth_options = {}
-      self.ancestry_base_class.scope_depth(depth_options, depth).ordered_by_ancestry.where  ancestor_conditions
+      self.ancestry_base_class.scope_depth(depth_options, depth).ordered_by_ancestry.where ancestor_conditions
+    end
+
+    def ancestor_was_conditions
+      {primary_key_with_table => ancestor_ids_was}
+    end
+
+    def ancestor_ids_was
+      parse_ancestry_column(changed_attributes[self.ancestry_base_class.ancestry_column.to_s])
     end
 
     def path_ids

test/has_ancestry_test.rb

@@ -810,4 +810,48 @@ def test_sort_by_ancestry_with_block
       assert_equal [n1, n3, n5, n2, n4, n6].map(&:id), arranged.map(&:id)
     end
   end
+
+  def test_touch_option_disabled
+    AncestryTestDatabase.with_model(
+      :extra_columns => {:name => :string, :updated_at => :datetime},
+      :touch => false
+    ) do |model|
+
+      yesterday = Time.now - 1.day
+      parent = model.create!(:updated_at => yesterday)
+      child  = model.create!(:updated_at => yesterday, :parent => parent)
+
+      child.update_attributes(:name => "Changed")
+      assert_equal yesterday, parent.updated_at
+    end
+  end
+
+  def test_touch_option_enabled
+    AncestryTestDatabase.with_model(
+      :extra_columns => {:updated_at => :datetime},
+      :touch => true
+    ) do |model|
+
+      way_back = Time.new(1984)
+      recently = Time.now - 1.minute
+
+      parent_1         = model.create!(:updated_at => way_back)
+      parent_2         = model.create!(:updated_at => way_back)
+      child_1_1        = model.create!(:updated_at => way_back, :parent => parent_1)
+      child_1_2        = model.create!(:updated_at => way_back, :parent => parent_1)
+      grandchild_1_1_1 = model.create!(:updated_at => way_back, :parent => child_1_1)
+      grandchild_1_1_2 = model.create!(:updated_at => way_back, :parent => child_1_1)
+
+      grandchild_1_1_1.parent = parent_2
+      grandchild_1_1_1.save!
+
+      assert grandchild_1_1_1.reload.updated_at > recently, "record was not touched"
+      assert child_1_1.reload.updated_at        > recently, "old parent was not touched"
+      assert parent_1.reload.updated_at         > recently, "old grandparent was not touched"
+      assert parent_2.reload.updated_at         > recently, "new parent was not touched"
+
+      assert_equal way_back, grandchild_1_1_2.reload.updated_at, "old sibling was touched"
+      assert_equal way_back, child_1_2.reload.updated_at,        "unrelated record was touched"
+    end
+  end
 end