Caveats for st.rerun

st.rerun is one of the tools to control the logic of your app. While it is great for prototyping, there can be adverse side effects:

• Additional script runs may be inefficient and slower.
• Excessive reruns may complicate your app’s logic and be harder to follow.
• If misused, infinite looping may crash your app.

In many cases where st.rerun works, callbacks may be a cleaner alternative. Containers may also be helpful.

A simple example in three variations

Using st.rerun to update an earlier header

import streamlit as st

if "value" not in st.session_state:
    st.session_state.value = "Title"

##### Option using st.rerun #####
st.header(st.session_state.value)

if st.button("Foo"):
    st.session_state.value = "Foo"
    st.rerun()

Using a callback to update an earlier header

##### Option using a callback #####
st.header(st.session_state.value)

def update_value():
    st.session_state.value = "Bar"

st.button("Bar", on_click=update_value)

Using containers to update an earlier header

##### Option using a container #####
container = st.container()

if st.button("Baz"):
    st.session_state.value = "Baz"

container.header(st.session_state.value)