Streamlit not recognising changes to st.session_state variable and hard coded variable when redirecting user

🎈 Using Streamlit
1

Summary

When using st.markdown or components.v1.html in order to redirect my users programmatically to another website or server - mimicking the fact a user has already logged in and so redirect them to the main app page - when I go back to the login page and mimic the change in auth status, it appears the changes are not implemented. Streamlit acts as if the previous value - False is still the same value despite my changing the value to True.

Steps to reproduce

Code snippet:

import streamlit as st

def nav_to(url):
    nav_script = """
        <meta http-equiv="refresh" content="0; url='%s'">
    """ % (url)
    st.write(nav_script, unsafe_allow_html=True)

if "sessionCookie" not in st.session_state:
    st.session_state["sessionCookie"] = None

# value will come from database for example but for this purposes its hard coded.
st.session_state["sessionCookie"] = True

if st.session_state["sessionCookie"]:
   # redirect user to server hosting main app page
   nav_to("www.google.co.uk") # using google for simplicity's sake
else:
    st.write("Need to authenticate") # login page will render here

second run - mimicking a user who has not been authenticated

The same as the above only sessionCookie will be False

# value will come from database for example but for this purposes its hard coded.
st.session_state["sessionCookie"] = False

Expected behavior:

I expect that when I go back to the login page url, with a new sessionCookie value - False it should render the login page.

Actual behavior:

But it still renders the redirect section even when I change its from True to False - again to mimic getting the dynamic data from database. At the initial run, I used a print statement to print out the “cookieSession” from st.session_state and depsite changing the value it still shows the intiial value.

I also tested it with a variable rather than st.session_state for example verified = False instead of st.session_state["sessionCookie"] = False.

Debug info

  • Streamlit version: 1.27.0
  • Python version: 3.9
  • Using Conda
  • OS version: Windows 11
  • Browser version: Version 117.0.5938.92 (Official Build)

Requirements file

conda

Links

  • Link to your GitHub repo:
  • Link to your deployed app:

Additional information

I tested the above using other methods like:

Method #2

Create an a tag then mimic “clicking” it if verified status is True to redirect to main app page. Again using hard coded variable and st.session_state saved variable.


verified = True 
st.markdown("<a class='redirect' href='https://google.co.uk'></a> ", unsafe_allow_html=True)

js = f'''
            <script>
                function redirect(event) {{
                    window.top.parent.document.querySelectorAll('[class="redirect"]')[0].click();
                    event.preventDefault();
                }}
                if ({verified} === True){{
              
                  redirect();
                   }}

           </script>
  '''

st.components.v1.html(js, height=0, width=0)

Method 3

Use javascript to create the meta tag and append to head element. Again using hard coded variable and st.session_state saved variable.

st.session_state["sessionCookie"] = True

  js =  f""" 
        <script>
           if ({st.session_state["sessionCookie"]} === True){{
               const redirect_link = document.createElement('meta');
               redirect_link.httpEquiv = "refresh";
               redirect_link.content = "20; URL='https://google.co.uk'";
               window.top.document.head.appendChild(redirect_link);
           }} else {{
               redirectMeta = window.top.parent.document.querySelectorAll('meta[httpEquiv="refresh"]')[0];
               redirectMeta.remove();
            }}
        </script>
"""
st.components.v1.html(js, height=0, width=0)

In all cases when I change the verified/cookie status the value remained the same as it was upon initiation. Any idea why these changes are not being recognised by streamlit?

2

Nvm, works as expected. Changes needed to be made whilst the page was active - ie whilst on localhost:8501 for example. I placed a longer delay on the redirect and changed it before it activated and it worked. I also tested it with expiring cookies and it worked when it could not find it in the browser.

All’s good.