Delete nested elements quickly

app/models/alchemy/element.rb

@@ -70,6 +70,8 @@ class Element < BaseRecord
 
     has_many :contents, dependent: :destroy, inverse_of: :element
 
+    before_destroy :delete_all_nested_elements
+
     has_many :all_nested_elements,
       -> { order(:position) },
       class_name: "Alchemy::Element",
@@ -347,5 +349,18 @@ def touch_touchable_pages
 
       touchable_pages.each(&:touch)
     end
+
+    def delete_all_nested_elements
+      deeply_nested_elements = descendent_elements(self).flatten
+      DeleteElements.new(deeply_nested_elements).call
+      nested_elements.reset
+      all_nested_elements.reset
+    end
+
+    def descendent_elements(element)
+      element.all_nested_elements + element.all_nested_elements.map do |nested_element|
+        descendent_elements(nested_element)
+      end
+    end
   end
 end

spec/models/alchemy/element_spec.rb

@@ -968,4 +968,18 @@ module Alchemy
       end
     end
   end
+
+  describe "destroy callbacks" do
+    let(:element) { create(:alchemy_element) }
+    let!(:nested_element_1) { create(:alchemy_element, parent_element: element) }
+    let!(:nested_element_2) { create(:alchemy_element, parent_element: nested_element_1) }
+    let!(:nested_element_3) { create(:alchemy_element, parent_element: nested_element_2) }
+
+    it "destroys all the nested elements quickly" do
+      expect(Alchemy::DeleteElements).to receive(:new).with(
+        [nested_element_1, nested_element_2, nested_element_3]
+      ).and_call_original
+      element.reload.destroy!
+    end
+  end
 end