VBox is not working in 3.4.0rc1

[GillesFa]

Hi,
I have install the following bokeh version:

Python version : 3.11.5 | packaged by Anaconda, Inc. | (main, Sep 11 2023, 13:26:23) [MSC v.1916 64 bit (AMD64)]
IPython version : 8.17.2
Tornado version : 6.3.3
Bokeh version : 3.4.0rc1
BokehJS static path : C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\server\static
node.js version : (not installed)
npm version : (not installed)
jupyter_bokeh version : (not installed)
Operating system : Windows-10-10.0.19045-SP0

I am trying to use a VBox layout but when I run my attached example, I get the following error:

Traceback (most recent call last):
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\runpy.py", line 198, in _run_module_as_main
return _run_code(code, main_globals, None,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\runpy.py", line 88, in run_code
exec(code, run_globals)
File "c:\Users\gilles.faure.vscode\extensions\ms-python.python-2024.0.1\pythonFiles\lib\python\debugpy\adapter/../..\debugpy\launcher/../..\debugpy_main.py", line 39, in
cli.main()
File "c:\Users\gilles.faure.vscode\extensions\ms-python.python-2024.0.1\pythonFiles\lib\python\debugpy\adapter/../..\debugpy\launcher/../..\debugpy/..\debugpy\server\cli.py", line 430, in main
run()
File "c:\Users\gilles.faure.vscode\extensions\ms-python.python-2024.0.1\pythonFiles\lib\python\debugpy\adapter/../..\debugpy\launcher/../..\debugpy/..\debugpy\server\cli.py", line 284, in run_file
runpy.run_path(target, run_name="main")
File "c:\Users\gilles.faure.vscode\extensions\ms-python.python-2024.0.1\pythonFiles\lib\python\debugpy_vendored\pydevd_pydevd_bundle\pydevd_runpy.py", line 321, in run_path
return _run_module_code(code, init_globals, run_name,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "c:\Users\gilles.faure.vscode\extensions\ms-python.python-2024.0.1\pythonFiles\lib\python\debugpy_vendored\pydevd_pydevd_bundle\pydevd_runpy.py", line 135, in _run_module_code
_run_code(code, mod_globals, init_globals,
File "c:\Users\gilles.faure.vscode\extensions\ms-python.python-2024.0.1\pythonFiles\lib\python\debugpy_vendored\pydevd_pydevd_bundle\pydevd_runpy.py", line 124, in _run_code
exec(code, run_globals)
File "C:\Development\Net-Zero_Energy_Networks\energy_optimisation\scratch\bokeh_vbox_issue.py", line 9, in
show(vbox)
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\io\showing.py", line 149, in show
return _show_with_state(obj, state, browser, new, notebook_handle=notebook_handle)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\io\showing.py", line 200, in _show_with_state
_show_file_with_state(obj, state, new, controller)
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\io\showing.py", line 181, in _show_file_with_state
filename = save(obj, state=state)
^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\io\saving.py", line 98, in save
_save_helper(obj, filename, resources, title, template, theme)
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\io\saving.py", line 164, in _save_helper
html = file_html(obj, resources=resources, title=title, template=template or FILE, theme=theme)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\embed\standalone.py", line 358, in file_html
with OutputDocumentFor(models_seq, apply_theme=theme, always_new=_always_new) as doc:
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\contextlib.py", line 137, in enter
return next(self.gen)
^^^^^^^^^^^^^^
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\embed\util.py", line 175, in OutputDocumentFor
doc.validate()
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\document\document.py", line 787, in validate
issues = check_integrity(refs)
^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\core\validation\check.py", line 171, in check_integrity
issues.error.extend(func())
^^^^^^
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\core\validation\decorators.py", line 74, in _wrapper
extra = func(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\models\layouts.py", line 458, in _check_repeated_layout_children
children = [ item["child"] for item in self.items ]
^^^^^^^^^^
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\core\has_props.py", line 371, in getattr
self._raise_attribute_error_with_matches(name, properties)
File "C:\Users\gilles.faure\AppData\Local\miniconda3\envs\EO_py3.11\Lib\site-packages\bokeh\core\has_props.py", line 379, in _raise_attribute_error_with_matches
raise AttributeError(f"unexpected attribute {name!r} to {self.class.name}, {text} attributes are {nice_join(matches)}")
AttributeError: unexpected attribute 'items' to VBox, possible attributes are align, aspect_ratio, children, context_menu, css_classes, css_variables, disabled, elements, flow_mode, height, height_policy, js_event_callbacks, js_property_callbacks, margin, max_height, max_width, min_height, min_width, name, resizable, rows, sizing_mode, spacing, styles, stylesheets, subscribed_events, syncable, tags, visible, width or width_policy

Could you advise what is the issue with my code?
thanks
Gilles

ps: couldn't attached the py file so here the code:

from bokeh.plotting import show
from bokeh.models import TextInput
from bokeh.models import VBox



text_input = TextInput(value="default", title="Label:")
vbox = VBox(children=[text_input])
show(vbox)

[bryevdv]

@GillesFa The error tries to be self-explanatory:

AttributeError: unexpected attribute 'items' to VBox

Perhaps you mean to set the children property, which does exist?

bokeh/src/bokeh/models/layouts.py

Lines 444 to 446 in 8a5a35e

	children = List(Struct(child=Instance(UIElement), row=Optional(Int), span=Optional(Int)), default=[], help="""
	A list of children with their associated position in the vertical box (optional; row number, span).
	""").accepts(List(Instance(UIElement)), lambda children: [ dict(child=child) for child in children ])

[GillesFa]

isn't it what I am doing?
vbox = VBox(children=[text_input])

[bryevdv]

My apologies, indeed you are. That's a bug in the validator:

bokeh/src/bokeh/models/layouts.py

Lines 456 to 460 in 8a5a35e

	@error(REPEATED_LAYOUT_CHILD)
	def _check_repeated_layout_children(self):
	children = [ item["child"] for item in self.items ]
	if len(children) != len(set(children)):
	return str(self)