Can we specify the property using a getter/setter in `st_stateful`? To deal with objects where the the properties are nested

[andehr]

streamlit-helpers/streamlithelpers/streamlit_helpers.py

Lines 192 to 269 in 6f33eec

	def st_stateful(widget_func, prop, obj, post_change: Callable = None, change_args: tuple[Any, ...] = None,
	change_kwargs: dict[str, Any] = None, **kwargs):
	"""
	Given a streamlit widget function, a property name and a reference to a SessionObject value on which the property
	value belongs, create a stateful widget that will store the value of the widget in the SessionObject property, and
	set itself to the value of the property even between page switches, by using an explicit session state property for
	the widget.
	:param widget_func: The streamlit widget function to use (e.g. st.checkbox, st.selectbox, etc.)
	:param prop: The name of a property on an object that is stored using SesssionObject
	:param obj: The object with the above property (that is stored using SessionObject)
	:param kwargs: The keyword arguments to pass to the widget function
	:param post_change: A function to run after the widget value has changed
	:param change_args: The arguments to pass to the post_change function
	:param change_kwargs: The keyword arguments to pass to the post_change function
	NOTE:
	1. on_change, value and index parameters of the widget function are set by this function and should therefore not be passed in kwargs.
	2. You can set the label of your widget by passing a 'label' parameter in kwargs, or as the first argument in args.
	3. The default session state key is a combination of the object name, the property name and the widget function name, but you can pass a key parameter in kwargs to override this.
	Usage example:
	```
	@SessionObject("my_session_object")
	def session_user_defined(value: UserDefined) -> UserDefined:
	return value
	# initialise if necessary
	session_user_defined.init(UserDefined())
	# get current value of the session object
	current_value = session_user_defined.get()
	# create a stateful checkbox widget that will store its value in the example 'enabled' property of the UserDefined object
	current_value = st_stateful(st.checkbox, "enabled", current_value, label="Enable feature")
	```
	Then you can either access the value using current_value.enabled, or by assigning the result of the st_stateful call
	TODO: can all the default stuff be done by setting the session state value when None?
	"""
	session_state_key = kwargs.pop("key", f"{type(obj).__name__}_{prop}_{widget_func.__name__}")
	def store_prop():
	"""
	Function sets the value of the SessionObject's property to the value of the widget.
	This function will run on the on_change event of the widget before refresh
	"""
	current_val = st.session_state[session_state_key]
	setattr(obj, prop, current_val)
	if post_change is not None:
	post_change(current_val, *(change_args or ()), **(change_kwargs or {}))
	# if the args list is empty and no label is specified in kwargs, use the property name as the label
	if "label" not in kwargs:
	kwargs["label"] = prop
	# if the widget is a selectbox or radio (i.e. a widget requiring the 'options' param), try to set the index of the widget (i.e. default value) to the index of the current value of the property in question
	if widget_func.__name__ in {"selectbox", "radio"}:
	try:
	kwargs["index"] = kwargs.get("options").index(getattr(obj, prop))
	except ValueError:
	# if the current value of the property is not in the options list, set the index to 0 and update the object's property to that value
	if kwargs.get("options", []):
	kwargs["index"] = 0
	setattr(obj, prop, kwargs.get("options")[0])
	# if the widget is a segmented control
	elif widget_func.__name__ in {"segmented_control"}:
	kwargs["default"] = getattr(obj, prop)
	# otherwise, set the value parameter of the widget directly to the value of the property of the SessionObject
	else:
	kwargs["value"] = getattr(obj, prop)
	# returns the value of the widget, and sets the value of the widget to the value of the property of the SessionObject
	return widget_func(key=session_state_key, on_change=store_prop, **kwargs)