Fix NestedSelect update options

panel/tests/ui/widgets/test_select.py

@@ -1,7 +1,9 @@
 import pytest
 
+from playwright.sync_api import expect
+
 from panel.tests.util import serve_component, wait_until
-from panel.widgets import MultiSelect, Select
+from panel.widgets import MultiSelect, NestedSelect, Select
 
 pytestmark = pytest.mark.ui
 
@@ -31,3 +33,14 @@ def test_multi_select_double_click(page):
     page.locator('option').nth(1).dblclick()
 
     wait_until(lambda: bool(clicks) and clicks[0].option == 'B', page)
+
+
+def test_nested_select_update_options(page):
+    n = NestedSelect(options={"a": {"b": ["c", "d"]}})
+
+    serve_component(page, n)
+
+    expect(page.locator('option').first).to_have_text("a")
+
+    n.options = {"c": {"d": ["e", "f"]}}
+    expect(page.locator('option').first).to_have_text("c")

panel/tests/widgets/test_select.py

@@ -800,8 +800,8 @@ def test_nested_select_layout_dict(document, comm):
         options=options,
         layout={"type": GridBox, "ncols": 2},
     )
-    assert isinstance(select._composite, GridBox)
-    assert select._composite.ncols == 2
+    assert isinstance(select._composite[0], GridBox)
+    assert select._composite[0].ncols == 2
 
 
 def test_nested_select_layout_dynamic_update(document, comm):
@@ -819,8 +819,8 @@ def test_nested_select_layout_dynamic_update(document, comm):
         options=options,
         layout={"type": GridBox, "ncols": 2},
     )
-    assert isinstance(select._composite, GridBox)
-    assert select._composite.ncols == 2
+    assert isinstance(select._composite[0], GridBox)
+    assert select._composite[0].ncols == 2
 
     select.layout = Row
     assert isinstance(select._composite, Row)

panel/widgets/select.py

@@ -522,7 +522,7 @@ def _update_widgets(self):
                 f"The layout must be a subclass of ListLike or dict, got {self.layout!r}."
             )
 
-        self._composite = layout_type(*self._widgets, **layout_kwargs)
+        self._composite[:] = [layout_type(*self._widgets, **layout_kwargs)]
         if self.options is not None:
             self.value = self._gather_values_from_widgets()