Utility function to update PxeMenu list

With this commit we introduce a utility method on PxeServer model
to handle PxeMenus list update. Until now, miq-api was always
recreating all menus upon server update, but often we can actually
just preserve exisitng menus. This method calculates what menus to
add, what to preserve and what to remove, and then executes it.

Fixes #18940

Signed-off-by: Miha Pleško <[email protected]>

app/models/pxe_server.rb

@@ -198,6 +198,14 @@ def delete_provisioning_files(pxe_image, mac_address, windows_image = nil, custo
     _log.info("#{log_message}...Complete")
   end
 
+  def ensure_menu_list(menu_list)
+    current_menus = pxe_menus.map(&:file_name)
+    to_destroy = current_menus.reject { |menu| menu_list.include?(menu) }
+    to_create = menu_list.reject { |menu| current_menus.include?(menu) }
+    pxe_menus.where(:file_name => to_destroy).destroy_all
+    to_create.each { |menu| pxe_menus << PxeMenu.create(:file_name => menu) }
+  end
+
   def self.display_name(number = 1)
     n_('PXE Server', 'PXE Servers', number)
   end

spec/models/pxe_server_spec.rb

@@ -4,6 +4,8 @@
     @pxe_server = FactoryBot.create(:pxe_server)
   end
 
+  subject { FactoryBot.create(:pxe_server) }
+
   context "#sync_images_queue" do
     it "should create a queue entry with the correct parameters" do
       msg = @pxe_server.sync_images_queue
@@ -310,4 +312,65 @@ def file_write(file, contents)
       expect(@pxe_server.discovered_pxe_images).to eq([@discovered_image])
     end
   end
+
+  describe '#ensure_menu_list' do
+    context 'when creating server' do
+      subject { FactoryBot.build(:pxe_server) }
+      it 'existing menus remain' do
+        subject.ensure_menu_list(%w[new])
+        expect(PxeMenu.count).to eq(1)
+      end
+    end
+
+    context 'when updating server' do
+      let!(:pxe_menu_1)  { FactoryBot.create(:pxe_menu, :pxe_server => subject, :file_name => 'existing1') }
+      let!(:pxe_image_1) { FactoryBot.create(:pxe_image, :pxe_server => subject, :pxe_menu => pxe_menu_1) }
+      let!(:pxe_menu_2)  { FactoryBot.create(:pxe_menu, :pxe_server => subject, :file_name => 'existing2') }
+      let!(:pxe_image_2) { FactoryBot.create(:pxe_image, :pxe_server => subject, :pxe_menu => pxe_menu_2) }
+
+      context 'when nothing changed' do
+        let(:menus) { %w[existing1 existing2] }
+        it 'all menus remain' do
+          subject.ensure_menu_list(menus)
+          expect(PxeMenu.count).to eq(2)
+          expect(PxeImage.count).to eq(2)
+          expect(PxeMenu.find_by(:id => pxe_menu_1.id)).to eq(pxe_menu_1)
+          expect(PxeMenu.find_by(:id => pxe_menu_2.id)).to eq(pxe_menu_2)
+        end
+      end
+
+      context 'when new menus are added' do
+        let(:menus) { %w[existing1 existing2 new] }
+        it 'existing menus remain' do
+          subject.ensure_menu_list(menus)
+          expect(PxeMenu.count).to eq(3)
+          expect(PxeImage.count).to eq(2)
+          expect(PxeMenu.find_by(:id => pxe_menu_1.id)).to eq(pxe_menu_1)
+          expect(PxeMenu.find_by(:id => pxe_menu_2.id)).to eq(pxe_menu_2)
+          expect(PxeMenu.find_by(:file_name => 'new')).not_to be_nil
+        end
+      end
+
+      context 'when menus are deleted' do
+        let(:menus) { %w[existing1] }
+        it 'menus are destroyed' do
+          subject.ensure_menu_list(menus)
+          expect(PxeMenu.count).to eq(1)
+          expect(PxeImage.count).to eq(1)
+          expect(PxeMenu.find_by(:id => pxe_menu_1.id)).to eq(pxe_menu_1)
+          expect(PxeMenu.find_by(:id => pxe_menu_2.id)).to be_nil
+        end
+      end
+
+      context 'when different menus are specified' do
+        let(:menus) { %w[new] }
+        it 'old menus are destroyed' do
+          subject.ensure_menu_list(menus)
+          expect(PxeMenu.count).to eq(1)
+          expect(PxeImage.count).to eq(0)
+          expect(PxeMenu.find_by(:file_name => 'new')).not_to be_nil
+        end
+      end
+    end
+  end
 end