recursively undo cloned trees

Fixes: #3684.
Relates to: #3652

The issue was that when we locked a form with an input inside where the
input changed, the form was cloned and then later the input inside was
cloned as well, stored inside the already cloned parent. When undoing,
previously the simple patch copied over the PHX_PRIVATE of the cloned
elements, but with the full DOMPatch, the privates of the source element
were copied, discarding the clone of the input. With this change, we check
if we are undoing locks and manually copy over nested clones to ensure
that they can be correctly applied afterwards.

assets/js/phoenix_live_view/dom_patch.js

@@ -218,7 +218,7 @@ export default class DOMPatch {
           let isFocusedFormEl = focused && fromEl.isSameNode(focused) && DOM.isFormInput(fromEl)
           let focusedSelectChanged = isFocusedFormEl && this.isChangedSelect(fromEl, toEl)
           // only perform the clone step if this is not a patch that unlocks
-          if(fromEl.hasAttribute(PHX_REF_SRC) && fromEl.getAttribute(PHX_REF_LOCK) != this.undoRef){
+          if(fromEl.hasAttribute(PHX_REF_SRC) && !this.undoRef){
             if(DOM.isUploadInput(fromEl)){
               DOM.mergeAttrs(fromEl, toEl, {isIgnored: true})
               this.trackBefore("updated", fromEl, toEl)
@@ -245,7 +245,11 @@ export default class DOMPatch {
             return false
           }
 
-          // input handling
+          // if we are undoing a lock, copy potentially nested clones over
+          if(this.undoRef && DOM.private(toEl, PHX_REF_LOCK)) {
+            DOM.putPrivate(fromEl, PHX_REF_LOCK, DOM.private(toEl, PHX_REF_LOCK))
+          }
+          // now copy regular DOM.private data
           DOM.copyPrivates(toEl, fromEl)
 
           // skip patching focused inputs unless focus is a select that has changed options

test/e2e/support/issues/issue_3684.ex

@@ -0,0 +1,105 @@
+defmodule Phoenix.LiveViewTest.E2E.Issue3684Live do
+  # https://github.com/phoenixframework/phoenix_live_view/issues/3684
+  use Phoenix.LiveView
+
+  defmodule BadgeForm do
+    use Phoenix.LiveComponent
+
+    def mount(socket) do
+      socket =
+        socket
+        |> assign(:type, :huey)
+
+      {:ok, socket}
+    end
+
+    def update(assigns, socket) do
+      socket =
+        socket
+        |> assign(:form, assigns.form)
+
+      {:ok, socket}
+    end
+
+    def render(assigns) do
+      ~H"""
+      <div>
+        <.form
+          for={@form}
+          id="foo"
+          class="max-w-lg p-8 flex flex-col gap-4"
+          phx-change="change"
+          phx-submit="submit"
+        >
+          <.radios type={@type} form={@form} myself={@myself} />
+        </.form>
+      </div>
+      """
+    end
+
+    defp radios(assigns) do
+      ~H"""
+      <fieldset>
+        <legend>Radio example:</legend>
+        <%= for type <- [:huey, :dewey] do %>
+          <div
+            phx-click="change-type"
+            phx-value-type={type}
+            phx-target={@myself}
+          >
+            <input
+              type="radio"
+              id={type}
+              name="type"
+              value={type}
+              checked={@type == type}
+            />
+            <label for={type}>{type}</label>
+          </div>
+        <% end %>
+      </fieldset>
+      """
+    end
+
+    def handle_event("change-type", %{"type" => type}, socket) do
+      type = String.to_existing_atom(type)
+      socket = assign(socket, :type, type)
+      {:noreply, socket}
+    end
+  end
+
+  defp changeset(params) do
+    data = %{}
+
+    types = %{
+      type: :string
+    }
+
+    {data, types}
+    |> Ecto.Changeset.cast(params, Map.keys(types))
+    |> Ecto.Changeset.validate_required(:type)
+  end
+
+  def mount(_params, _session, socket) do
+    {:ok, assign(socket, form: to_form(changeset(%{}), as: :foo), payload: nil)}
+  end
+
+  def render(assigns) do
+    ~H"""
+    <.live_component
+      id="badge_form"
+      module={__MODULE__.BadgeForm}
+      action={@live_action}
+      form={@form}
+    />
+    """
+  end
+
+  def handle_event("change", params, socket) do
+    {:noreply, socket}
+  end
+
+  def handle_event("submit", params, socket) do
+    {:noreply, socket}
+  end
+end

test/e2e/test_helper.exs

@@ -162,6 +162,7 @@ defmodule Phoenix.LiveViewTest.E2E.Router do
       live "/3651", Issue3651Live
       live "/3656", Issue3656Live
       live "/3658", Issue3658Live
+      live "/3684", Issue3684Live
     end
   end
 

test/e2e/tests/issues/3684.spec.js

@@ -0,0 +1,15 @@
+const {test, expect} = require("../../test-fixtures")
+const {syncLV} = require("../../utils")
+
+// https://github.com/phoenixframework/phoenix_live_view/issues/3684
+test("nested clones are correctly applied", async ({page}) => {
+  await page.goto("/issues/3684")
+  await syncLV(page)
+
+  await expect(page.locator("#dewey")).not.toHaveAttribute("checked")
+
+  await page.locator("#dewey").click();
+  await syncLV(page);
+
+  await expect(page.locator("#dewey")).toHaveAttribute("checked")
+})