using-streamlit-session-state

You persist Streamlit widget values across reruns by storing them in st.session_state, which prevents variables from resetting when the script executes top-to-bottom on every user interaction. Assign widget keys to synchronize and retain their specific values automatically.

Your Streamlit app resets variables because it reruns the entire script top-to-bottom on each interaction. You need to use st.session_state to persist per-user UI state and arbitrary data, keeping your dashboard or web app consistent throughout these reruns.

The best way to initialize session state in a Streamlit multi-page app is using st.session_state.setdefault("value", 0). This initialization pattern safely establishes default values without overwriting existing ones, ensuring robust cross-page state synchronization.

You sync Streamlit widgets with session state keys by assigning a unique key parameter to each widget. This synchronization links the widget directly to st.session_state, enabling per-user state retention and safe, callback-driven updates across your web app.

Yes, you can use callbacks to safely update Streamlit session state. Callback-driven updates ensure that widget interactions modify st.session_state values securely during reruns, providing debugging tips and initialization patterns for robust multi-page applications.