Hi all,
I have a problem when using a session state implementation for pre-selection of multiselect options.
When I enter some text in the text_input, it changes the session state and does a rerun/sync. After the sync, the front-end and back-end of the checkbox below are out of sync.
Please have a look at my screen cast:
the code for this test app is here:
import re
import streamlit as st
from sessionstate import _get_state
session_state = _get_state()
session_state.input_value = ''
input_value = st.text_input('regex for multiselect', value=session_state.input_value)
session_state.input_value = input_value
session_state.sync()
options = ['test1', 'test2', 'test3', 'test4']
preselected = [x for x in options if re.match(input_value, x) and input_value != '']
multiselect_value = st.multiselect('multiselect', options=options, default=preselected)
st.markdown('Value of multiselect')
st.write(multiselect_value)
checkbox_value = st.checkbox('checkbox', value=True)
st.markdown('Value of checkbox')
st.write(checkbox_value)
the code for the session state is here (found it somewhere in this forum):
from streamlit.report_thread import get_report_ctx
from streamlit.hashing import _CodeHasher
from streamlit.server.server import Server
class _SessionState:
def __init__(self, session, hash_funcs):
"""Initialize sessionstate instance."""
self.__dict__["_state"] = {
"data": {},
"hash": None,
"hasher": _CodeHasher(hash_funcs),
"is_rerun": False,
"session": session,
}
def __call__(self, **kwargs):
"""Initialize state data once."""
for item, value in kwargs.items():
if item not in self._state["data"]:
self._state["data"][item] = value
def __getitem__(self, item):
"""Return a saved state value, None if item is undefined."""
return self._state["data"].get(item, None)
def __getattr__(self, item):
"""Return a saved state value, None if item is undefined."""
return self._state["data"].get(item, None)
def __setitem__(self, item, value):
"""Set state value."""
self._state["data"][item] = value
def __setattr__(self, item, value):
"""Set state value."""
self._state["data"][item] = value
def clear(self):
"""Clear session state and request a rerun."""
self._state["data"].clear()
self._state["session"].request_rerun()
def sync(self):
"""Rerun the app with all state values up to date from the beginning to fix rollbacks."""
# Ensure to rerun only once to avoid infinite loops
# caused by a constantly changing state value at each run.
#
# Example: state.value += 1
if self._state["is_rerun"]:
self._state["is_rerun"] = False
elif self._state["hash"] is not None:
if self._state["hash"] != self._state["hasher"].to_bytes(self._state["data"], None):
self._state["is_rerun"] = True
self._state["session"].request_rerun()
self._state["hash"] = self._state["hasher"].to_bytes(self._state["data"], None)
def _get_session():
session_id = get_report_ctx().session_id
session_info = Server.get_current()._get_session_info(session_id)
if session_info is None:
raise RuntimeError("Couldn't get your Streamlit Session object.")
return session_info.session
def _get_state(hash_funcs=None):
session = _get_session()
if not hasattr(session, "_custom_session_state"):
session._custom_session_state = _SessionState(session, hash_funcs)
return session._custom_session_state