Multi-page app with session state

Codeguyross · July 27, 2020, 8:38pm

I am currently getting the follow error when trying to run this code:

'SessionState' object has no attribute 'input'

okld · July 28, 2020, 11:33am

Hello @Codeguyross,

Could you share your source code? It’d be easier to identify the problem.
My class has an underscore before SessionState. Maybe you tried to use this class along with Thiago’s ?

Gaurav_Gupta · July 28, 2020, 7:19pm

Hi @okld I am referring to this example to get better understanding of Session State Management

gist.github.com

https://gist.github.com/Ghasel/0aba4869ba6fdc8d49132e6974e2e662#file-st_demo_settings-py-L2

st_demo_settings.py

import streamlit as st
from streamlit.ReportThread import get_report_ctx
from streamlit.hashing import _CodeHasher
from streamlit.server.Server import Server


def main():
    state = _get_state()
    pages = {
        "Dashboard": page_dashboard,

This file has been truncated. show original

But after getting the return from the _get_state method , I can’t able to set the items to the SessionState class.

okld · July 28, 2020, 8:45pm

Hello @Gaurav_Gupta,

So you seem to have the same kind of error as @Codeguyross. In both cases, the exception is related to a SessionState object which I don’t use. In my code there is an underscore prepended: _SessionState.

Could you share your source code? I need more info to identify the issue.

Gaurav_Gupta · July 29, 2020, 5:14am

Hi @okld

github.com

gaurav-gunhawk/Python/blob/master/Streamlit/Streamlit-SessionStateManagement.py

import streamlit as st
import streamlit.ReportThread as ReportThread
from streamlit.server.Server import Server

radioButton = st.sidebar.radio("Go to",['Home', 'Page One'])

def get_session():
    ctx = ReportThread.get_report_ctx().session_id
    this_session = None
    current_session = Server.get_current()._get_session_info(ctx)
    this_session = current_session.session
    st.write("ch",current_session.session)

    if current_session is None:
        raise RuntimeError(
            "Oh noes. Couldn't get your Streamlit Session object"
            'Are you doing something fancy with threads?')

    return this_session

This file has been truncated. show original

okld · July 29, 2020, 9:16am

Hello @Gaurav_Gupta,

You have removed all the methods of my SessionState class in your code, no doubt it doesn’t function properly now ^^. The method which allows you to set new items in your class is __setattr__(). And you also need to access them by implementing __getattr__(). Include all the function I implemented (not only the 2 I mentioned), and it should work better.

And also, in your example you need to call state.sync() at the very end of your app to avoid rollback issues with your slider.

Gaurav_Gupta · July 29, 2020, 1:39pm

Hi @okld

I haven’t used that beacuse I can’t see that we are calling that methods anywhere.
If possible can you explain me briefly.

okld · July 29, 2020, 2:18pm

Methods surrounded by two underscores are called magic methods. Like the constructor __init__(), they’re not meant to be called explicitly in your code, but are used when you interact with an instance of your class in some specific ways.

Let’s say you have initialized a new state object with state = SessionState().
To summarize briefly what each method does:

__call__(self, arguments): called when you do state(arguments), you use state as if it was a function.
__getitem__(self, item): called when you do state["My item"]. In the function, item == "My item"
__getattr__(self, item): called when you do state.my_item. In the function, item == "my_item"
__setitem__(self, item, value): called when you do state["My item"] = "my value". In the function, value == "my value"
__setattr__(self, item, value): called when you do state.my_item = "my value". In the function, value == "my value"

There are more magic methods that I don’t use for other specific usages. You have some tutorials/blogs presenting and explaining more of them in details if you’re interested:

Gaurav_Gupta · July 29, 2020, 2:46pm

Hi @okld
Thanks for your kind. Now its done its working and maintaining the state too.

github.com

gaurav-gunhawk/Python/blob/master/Streamlit/Streamlit-SessionStateManagement.py

import streamlit as st
import streamlit.ReportThread as ReportThread
from streamlit.server.Server import Server

radioButton = st.sidebar.radio("Go to",['Home', 'Page One'])

def get_session():
    ctx = ReportThread.get_report_ctx().session_id
    this_session = None
    current_session = Server.get_current()._get_session_info(ctx)
    this_session = current_session.session
    st.write("ch",current_session.session)

    if current_session is None:
        raise RuntimeError(
            "Oh noes. Couldn't get your Streamlit Session object"
            'Are you doing something fancy with threads?')

    return this_session

This file has been truncated. show original

vnguyendc · August 14, 2020, 5:56pm

Hi @okld
After updating to the latest Streamlit version, I’ve came across an error
ModuleNotFoundError: No module named 'streamlit.ReportThread'

Have you implemented anything new to overcome this? Thanks.

okld · August 15, 2020, 11:57pm

Hello @vnguyendc,

I didn’t had time to check all the recent Streamlit changes, but with release 0.65 there was some code refactoring that broke session state implementations. I’ll work on it asap!

okld · August 16, 2020, 12:44am

Alright, I’ve made a quick (untested ) fix. I’ve walked through the new code, and there was no major change in the parts I use. Some python files were renamed, and updating the imports should be enough.

GokulNC · August 17, 2020, 9:03am

Thanks. Yes it works on v0.65.

Off-topic:
Is there a way to persist the session state across refreshes?
Maybe something like getting the device fingerprint should do right, instead of session id?
Is there a way for that? Or can it be added?

andfanilo · August 17, 2020, 9:08am

If memory serves me correctly, there’s another implementation of state with a GlobalState that is maintained between refreshes.

GokulNC · August 17, 2020, 9:16am

Great, thanks! That worked.
But it seems to be global for anyone accessing the page from anywhere.

This would be a good solution for that right?

andfanilo · August 17, 2020, 9:21am

It’s an interesting proposition…could you take this in another post on the forum so we don’t hijack this one too much ?

fdubinski · August 17, 2020, 6:56pm

I still get this error 'ModuleNotFoundError: No module named ‘streamlit.ReportThread’ after installing 0.65.0. Do i need to explicitly change anything in my code?

tuanvuvo · August 18, 2020, 4:36am

Hi @okld
Thanks for your sharing.
Can you share how can set up Session State for multi users working. As I use Session State of @thiago but session merge btw each users frequently

In my app, That’s embed in our ERP system, where one user click to Streamlit App, will have one auth_token in url para it’s user_id. But when other users come to same time, it’s will go to earler user session.

Do you have some advise for me?

AteBitHavoc · August 21, 2020, 10:14pm

I have been getting it aswell. Not sure how onerous it would be for your code, but you could always write the data using pickle and read it again when you need it at a later stage. Its how I over came this issue…not the most elegant solution but it worked…

okld · August 23, 2020, 6:58pm

Hmm, this is weird. Merging is not supposed to happen and may be related to another problem. Could you share some code reproducing the issue you’re encountering?

Topic		Replies	Views
Help with cache, callbacks or session state Using Streamlit cache	3	2243	August 16, 2023
Save widget state Using Streamlit	5	1768	August 15, 2022
Session_state - how to use it to save values while navigating through a multi_page app? Community Cloud session-state	4	1693	June 27, 2024
Session State Multi-page App MWE Using Streamlit session-state	0	495	August 15, 2021
Session State for Streamlit 🎈 Show the Community!	32	11233	September 28, 2023

Multi-page app with session state

Related topics

Hello there 👋🏻

Cookie settings

Strictly necessary cookies

Performance cookies

Functional cookies

Targeting cookies