St.data_editor within St.form not returning anything after clicking form_submit button

My code looks like as follow:

def run():
if st.sidebar.button('Run'):
st.session_state['data'] = function_run(arg1,arg2)

with st.form('data_editor_form'):
st.session_state['edited_df'] = st.data_editor(st.session_state['data'])

submit_button = st.form_submit_button('Update')

if submit_button:
st.session_state['edited_df'].to_csv('df.csv')

Expected Behavior: The dataframe should be visible in the browser using data_editor, user should be able to edit some cells as required, then press submit_button to export the edited file as csv.

Current Behavior: The dataframe is visible on the browser, user can edit it but once submit_button is clicked, it doesnt returns true, however the code starts re-running from the beginning include the function - ‘function_run’ and does not export the csv.

Could you please help on how can I achieve the expected behavior?

I have been through other topics on form and data_editor but none of the solution has helped.

It looks like there might be an issue with the way you are using st.session_state. The behavior you’re experiencing could be due to the fact that the st.data_editor creates a new form, and when the form is submitted, the entire app is rerun, including the function_run part.

Here’s a suggested modification to your code:

import streamlit as st

def run():
    if st.sidebar.button('Run'):
        st.session_state['data'] = function_run(arg1, arg2)

    with st.form('data_editor_form'):
        st.session_state['edited_df'] = st.data_editor(st.session_state['data'])
        submit_button = st.form_submit_button('Update')

    if submit_button:
        # Process the edited data
        edited_data = st.session_state['edited_df'].to_csv(index=False)
        # Save the edited data, for example to a CSV file
        with open('edited_data.csv', 'w') as f:
            f.write(edited_data)

if __name__ == '__main__':
    run()