How to append a list with new text inputs using button

Using Streamlit
1

I have just started exploring the streamlit, I liked the simplicity of this but one thing I am struggling right now with this is: any help is appreciated :slight_smile:
I have initialized a variable(list), and trying to update the list using the button.

> wt = ['initialised text']
> with watchlist:
>     st.header('Watchlist')
>     #create 2 columns inside watchlist header
>     col1 = st.beta_columns()
>     with col1:
>         container1 = st.beta_container()
>         sym = container1.text_input('for adding')
>         add_button = container2.button('add')
>         if add_button:
>             wt.append(sym)
> st.write(wt)

when I click add after giving a text input for example: ‘second text’
the output is:
[‘Initialised’, ‘second text’]

When I add some more text (Third text) into the list undesirable output is coming :
[‘Initialised’, ‘Third text’]

while my desirable output is :
[‘Initialised’, ‘second text’, ‘Third text’]

2 Likes
2

Hey @Prakhar_Gupta ,

Try using extend() instead of append(), like the following.

wt.extend(sym)
3

Using wt.extend() did not gage the result
Instead it seperated letters and put it in the list,
and the next string overrided previous one.

I want my initialised list wt to get updated, do you know any other possible solution?

5

Hey @Prakhar_Gupta ,
So this took me some time but I have found the solution, it’s a session state problem, basically when the page refreshes we lose what we appended into our list (wt), to solve that follow these steps:

  1. Copy this SessionState code (SessionState.py) into a .py page and name it SessionState.py in your project folder
  2. Here’s the code
import streamlit as st
import SessionState

wt = ['initialised text']
ss = SessionState.get(wt=wt)

st.header('Watchlist')

container1 = st.beta_container()
sym = container1.text_input('for adding')
container2 = st.beta_container()
add_button = container2.button('add')

if add_button:
    ss.wt.append(sym)

st.write(ss.wt)

Here is how it supposed to work.

watchList
watchList722×363 6.36 KB

Let us know if it worked perfectly for you!

1 Like
8

Hi @nainiayoub ,
I have tried the solution given by you and it worked.
But it is not working when I am trying to make two session state variables.

import streamlit as st
import SessionState

select_symbol = ['FIRST','SECOND','THIRD','FOURTH','FIVETH'] 
#used as options for symbol_input container's selectbox

#------------Initializing Two Session states------------
current_list = []
ss1 = SessionState.get(current_list=current_list)
#use ss1.current_list everywhere now

final_list = []
ss2 = SessionState.get(final_list=final_list)
#use ss2.final_list everywhere now


#------------ Create Containers----------------
watchlist_container = st.beta_container()
order_container = st.beta_container()

with watchlist_container:
    st.header('Watchlist')
    
    symbol_input = st.beta_container()
    sym = symbol_input.selectbox('Choose Symbols', options=select_symbol)
    
    
    buttons = st.beta_container()
    with buttons:
        # three buttons to add, delete, done
        add_button, delete_button, done_button  = st.beta_columns(3)
        add = add_button.button('add')
        delete = delete_button.button('delete')
        done = done_button.button('done')


if add:
    ss1.current_list.append(sym)
if delete:
    ss1.current_list.remove(sym)
st.write(ss1.current_list)

#Click on done saves current list to final list
if done:
    ss2.final_list.append(ss1.current_list)
    
    
with order_container:
    st.header('Order Here')
    # select a value from ss2.final_list
    selected = order_container.selectbox('order symbol', options=ss2.final_list)
    
    #Show final_list
    st.write(ss2.final_list)
    #Show selected value from final_list
    st.write(selected)

The above code is giving an attribute error:
AttributeError: ‘SessionState’ object has no attribute ‘final_list’

9

Hey @Prakhar_Gupta ,

I have answered you on your topic, hope that helps.

1 Like