2022-05-23 00:16:32 +04:00

142 lines
4.7 KiB
Python

# Copyright 2018-2022 Streamlit Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from typing import (
Any,
Dict,
Iterator,
MutableMapping,
)
import streamlit as st
from streamlit import logger as _logger
from streamlit.type_util import Key
from .safe_session_state import SafeSessionState
from .session_state import SessionState, require_valid_user_key
logger = _logger.get_logger(__name__)
_state_use_warning_already_displayed = False
def get_session_state() -> SafeSessionState:
"""Get the SessionState object for the current session.
Note that in streamlit scripts, this function should not be called
directly. Instead, SessionState objects should be accessed via
st.session_state.
"""
global _state_use_warning_already_displayed
from streamlit.scriptrunner import get_script_run_ctx
ctx = get_script_run_ctx()
# If there is no script run context because the script is run bare, have
# session state act as an always empty dictionary, and print a warning.
if ctx is None:
if not _state_use_warning_already_displayed:
_state_use_warning_already_displayed = True
if not st._is_running_with_streamlit:
logger.warning(
"Session state does not function when running a script without `streamlit run`"
)
return SafeSessionState(SessionState())
return ctx.session_state
class SessionStateProxy(MutableMapping[Key, Any]):
"""A stateless singleton that proxies `st.session_state` interactions
to the current script thread's SessionState instance.
The proxy API differs slightly from SessionState: it does not allow
callers to get, set, or iterate over "keyless" widgets (that is, widgets
that were created without a user_key, and have autogenerated keys).
"""
def __iter__(self) -> Iterator[Any]:
"""Iterator over user state and keyed widget values."""
# TODO: this is unsafe if fastReruns is true! Let's deprecate/remove.
return iter(get_session_state().filtered_state)
def __len__(self) -> int:
"""Number of user state and keyed widget values in session_state."""
return len(get_session_state().filtered_state)
def __str__(self) -> str:
"""String representation of user state and keyed widget values."""
return str(get_session_state().filtered_state)
def __getitem__(self, key: Key) -> Any:
"""Return the state or widget value with the given key.
Raises
------
StreamlitAPIException
If the key is not a valid SessionState user key.
"""
key = str(key)
require_valid_user_key(key)
return get_session_state()[key]
def __setitem__(self, key: Key, value: Any) -> None:
"""Set the value of the given key.
Raises
------
StreamlitAPIException
If the key is not a valid SessionState user key.
"""
key = str(key)
require_valid_user_key(key)
get_session_state()[key] = value
def __delitem__(self, key: Key) -> None:
"""Delete the value with the given key.
Raises
------
StreamlitAPIException
If the key is not a valid SessionState user key.
"""
key = str(key)
require_valid_user_key(key)
del get_session_state()[key]
def __getattr__(self, key: str) -> Any:
try:
return self[key]
except KeyError:
raise AttributeError(_missing_attr_error_message(key))
def __setattr__(self, key: str, value: Any) -> None:
self[key] = value
def __delattr__(self, key: str) -> None:
try:
del self[key]
except KeyError:
raise AttributeError(_missing_attr_error_message(key))
def to_dict(self) -> Dict[str, Any]:
"""Return a dict containing all session_state and keyed widget values."""
return get_session_state().filtered_state
def _missing_attr_error_message(attr_name: str) -> str:
return (
f'st.session_state has no attribute "{attr_name}". Did you forget to initialize it? '
f"More info: https://docs.streamlit.io/library/advanced-features/session-state#initialization"
)