refactor(element): Use folded_parent_element_ids for expanding nested elements

Only collect folded parent IDs when expanding an element, skipping
parents that are already expanded. This avoids unnecessary updates
and walks the tree with simple primary key lookups instead of loading
all elements for the page version into memory.

(cherry picked from commit 4129581)

Author: tvdeyen

app/controllers/alchemy/admin/elements_controller.rb

@@ -136,7 +136,7 @@ def expand
         @element.update_columns(folded: false)
         # We want to expand the upper most parent first in order to prevent
         # re-painting issues in the browser
-        parent_element_ids = @element.parent_element_ids.reverse
+        parent_element_ids = @element.folded_parent_element_ids.reverse
         Alchemy::Element.where(id: parent_element_ids).update_all(folded: false)
 
         render json: {

app/models/alchemy/element.rb

@@ -183,13 +183,21 @@ def all_from_clipboard_for_parent_element(clipboard, parent_element)
       end
     end
 
-    # Heavily unoptimized naive way to get all parent ids
-    def parent_element_ids
-      ids ||= []
-      parent = parent_element
-      while parent
-        ids.push parent.id
-        parent = parent.parent_element
+    # Returns IDs of all folded parent elements from immediate parent up to root
+    #
+    # Walks up the ancestor chain and collects only the ones that are folded,
+    # skipping already expanded parents.
+    #
+    # @return [Array<Integer>] Folded parent element IDs from immediate parent to root
+    def folded_parent_element_ids
+      return [] unless parent_element_id
+
+      ids = []
+      current_id = parent_element_id
+      while current_id
+        folded, parent_id = self.class.where(id: current_id).pick(:folded, :parent_element_id)
+        ids << current_id if folded
+        current_id = parent_id
       end
       ids
     end

spec/controllers/alchemy/admin/elements_controller_spec.rb

@@ -335,7 +335,7 @@ module Alchemy
 
         subject { post :expand, params: {id: nested_nested_folded_element.id} }
 
-        it "expands all parent elements" do
+        it "expands all folded parent elements" do
           subject
           aggregate_failures do
             expect(nested_element.reload).to_not be_folded
@@ -345,12 +345,11 @@ module Alchemy
           end
         end
 
-        it "returns json" do
+        it "returns json with only the folded parent element ids" do
           subject
           expect(JSON.parse(response.body)).to eq({
             "parentElementIds" => [
               element.id,
-              nested_element.id,
               nested_nested_element.id,
               nested_folded_element.id
             ],

spec/models/alchemy/element_spec.rb

@@ -633,15 +633,34 @@ module Alchemy
       end
     end
 
-    describe "#parent_element_ids" do
+    describe "#folded_parent_element_ids" do
       let(:page) { create(:alchemy_page) }
 
-      let!(:element1) { create(:alchemy_element, page_version: page.draft_version, name: "slider", autogenerate_nested_elements: false) }
-      let!(:element2) { create(:alchemy_element, page_version: page.draft_version, name: "slide", parent_element: element1) }
+      let!(:element1) { create(:alchemy_element, page_version: page.draft_version, name: "slider", folded: true, autogenerate_nested_elements: false) }
+      let!(:element2) { create(:alchemy_element, page_version: page.draft_version, name: "slide", folded: true, parent_element: element1) }
       let!(:element3) { create(:alchemy_element, page_version: page.draft_version, name: "slide", parent_element: element2) }
 
-      it "returns parent element ids" do
-        expect(element3.parent_element_ids).to eq([element2.id, element1.id])
+      it "returns folded parent element ids from immediate parent to root" do
+        expect(element3.folded_parent_element_ids).to eq([element2.id, element1.id])
+      end
+
+      it "returns empty array for root element" do
+        expect(element1.folded_parent_element_ids).to eq([])
+      end
+
+      it "returns single parent for first-level nested element" do
+        expect(element2.folded_parent_element_ids).to eq([element1.id])
+      end
+
+      it "skips already expanded parents" do
+        element2.update_columns(folded: false)
+        expect(element3.folded_parent_element_ids).to eq([element1.id])
+      end
+
+      it "returns empty array when all parents are expanded" do
+        element1.update_columns(folded: false)
+        element2.update_columns(folded: false)
+        expect(element3.folded_parent_element_ids).to eq([])
       end
     end