Any ideas how to take input from user then append to a list without losing the content of a list?

Iโ€™m very curious how to define a function that contains st.expander and a beginner code like take input, append to list (twice), show the list (with at least two items in it).

Thank you very much.

import streamlit as st


my_list = []


def manager():
    with st.expander("Example"):
        st.write(my_list)  #was
        user_input = st.text_input("Enter a key")
        add_button = st.button("Add", key='add_button')
        if add_button:
            if len(user_input) > 0:
                my_list.append(user_input)
                st.write(my_list)  #is
            else:
                st.warning("Enter text")


if __name__ == '__main__':
    manager()

@armM00

here you go:


import streamlit as st

# initiate empty list to add items to
lst = []

def append_to_lst(my_input=['test_input'], my_lst=lst):
    """
    Append items from the input list to the provided list and display the updated list in a Streamlit expander.

    Parameters:
        my_input (list): The list of items to be appended to the target list. Default is ['test_input'].
        my_lst (list): The target list to which the items will be appended. Default is lst.

    Returns:
        None

    """
    for my_item in my_input:
        my_lst.append(my_item)
    with st.expander('LIST', expanded=True):
        st.write(my_lst)
    
# apply function to add items to list  and show in streamlit list
append_to_lst(['test1', 'test2', 'test3'])
# apply function to add more items to list and show in streamlit list again
append_to_lst(['test4', 'test5', 'test6'])

Hi, thanks for your answer. However, I see you didnโ€™t implement user input that takes an input from a user and appends to a list. Sending you the code that needs an explaination.

P.S. Yes, this could be bypassed by storing the data in a file, however, thatโ€™s not likely. Moreover, I tried to make it in a while loop that non stop appends data to a list, streamlit couldnโ€™t handle that, just hang.

import streamlit as st


my_list = []


def manager():
    with st.expander("Example"):
        st.write(my_list)
        user_input = st.text_input("Enter a key")
        add_button = st.button("Add", key='add_button')
        if add_button:
            if len(user_input) > 0:
                my_list.append(user_input)
                st.write(my_list)
            else:
                st.warning("Enter text")


if __name__ == '__main__':
    manager()

@armM00 Thank you for your example code, that clarifies your goal. Below my example with using session state to store the list in:

import streamlit as st

if 'my_lst' not in st.session_state:
    st.session_state['my_lst'] = []

def manager():
    with st.expander("Example"):
        user_input = st.text_input("Enter a key")
        add_button = st.button("Add", key='add_button')
        if add_button:
            if len(user_input) > 0:
                st.session_state['my_lst'] += [user_input]
                st.write( st.session_state['my_lst'] )
            else:
                st.warning("Enter text")

if __name__ == '__main__':
    manager()

Let me know if that is what you wanted!

1 Like

Thank you.

This topic was automatically closed 2 days after the last reply. New replies are no longer allowed.