atexit registered function unable to access streamlit session state variable

Question

I have registered an atexit function like this:

import streamlit as st
from azure.search.documents.indexes import SearchIndexClient 
from azure.core.credentials import AzureKeyCredential
@atexit.register
def delete_vector_index():
 admin_client = SearchIndexClient(endpoint=st.session_state.vector_store_address,
 index_name=st.session_state.index_name,
 credential=AzureKeyCredential(st.session_state.vector_store_password))
 admin_client.delete_index(st.session_state.index_name)
if "initialized" not in st.session_state:
 st.session_state.initialized = True
 st.session_state.vector_store_address: str = "<my endpoint>"
 st.session_state.vector_store_password: str = "<admin key>"
 st.session_state.index_name: str = "<index name>"

But everytime the interpreter finishes, this is the error message I get "AttributeError: st.session_state has no attribute "vector_store_address". Did you forget to initialize it? More info: https://docs.streamlit.io/library/advanced-features/session-state#initialization"

Why is the st.session_state variable inaccessible from the atexit function when it can be easily accessed from my other functions? Does anyone know what to do about this?

Answer 1

The modified code below includes your code that accesses the Streamlit session state variable with the atexit function.

Code :

import atexit
import streamlit as st
from azure.search.documents.indexes import SearchIndexClient 
from azure.core.credentials import AzureKeyCredential
vector_store_address = None
vector_store_password = None
index_name = None
def delete_vector_index():
 if vector_store_address and vector_store_password and index_name:
 admin_client = SearchIndexClient(
 endpoint=vector_store_address,
 index_name=index_name,
 credential=AzureKeyCredential(vector_store_password)
 )
 admin_client.delete_index(index_name)
if "initialized" not in st.session_state:
 st.session_state.initialized = True
 vector_store_address = "https://<azure_search_name>.search.windows.net/"
 vector_store_password = "<azure_search_key>"
 index_name = "<index_name>"
atexit.register(delete_vector_index)
def main():
 st.title("Streamlit App")
if __name__ == "__main__":
 main()

Output :

It ran successfully as shown below:

enter image description here

I got the below output in the browser.

enter image description here

Next, the index was deleted while stopping Streamlit, as shown below.

enter image description here