Maintaining widget state across a multi-page Streamlit app

multipage_session_state.py

# Since widgets are created anew on each page their values will be initialized to their default values.
# I’ve created a separate ‘value cache’ to store values between pages.
# (Note, when a widget has a key and you initialize its value with a session state key value other than the widget’s own key value,
# Streamlit will complain. Therefore, the widgets don't have a key.)

import streamlit as st

# Instantiate the Session State Variables
if 'cache' not in st.session_state:
    st.session_state.cache = {'name': '', 'age': '', 'gender': ''}

# Sidebar Widgets

sidebar_Title = st.sidebar.markdown('# Streamlit')
sidebar_pages = st.sidebar.radio('Menu', ['Page 1', 'Page 2', 'Page 3'])

# Page 1
def page1():
    st.session_state.cache['name'] = st.text_input('What is your name?', value=st.session_state.cache['name'])

# Page 2
def page2():
    st.session_state.cache['age'] = st.text_input('What is your age?', value=st.session_state.cache['age'])

# Page 3
def page3():
    st.session_state.cache['gender'] = st.text_input('What is your gender?', value=st.session_state.cache['gender'])

# Navigate through pages

if sidebar_pages == 'Page 1':
    page1()
elif sidebar_pages == 'Page 2':
    page2()
else:
    page3()

st.write(st.session_state.cache)