Second if statement won't run after button click

🎈 Using Streamlit
1

I have this:

button1  =  st.button("Let's get started!")

if button1:
    user_csv = st.file_uploader("Upload your file here!", type="csv")

    if user_csv is not None:
        st.write("Amazing! Let me have a look at your file.")
        user_csv.seek(0)
        df = pd.read_csv(user_csv, low_memory=False)

But the second if statement won run and the file uploader disappears after clicking the button. Why is this happening and how to fix it? Thanks!

2

Buttons do not save their state, so after you interact with the any other component, the button goes back to False. Here is a better explanation of that behavior, in section 1. Buttons aren’t stateful:

1 Like
3

Hi @Ana_Rojo_Echeburua,

@edsaac response holds true.

You could also try something with callbacks, if suitable:

if "mydf" not in st.session_state: 
    st.session_state.mydf = pd.DataFrame()

def UploaderCallBack(somekey):
    if st.session_state[somekey] is not None:
        st.write("Amazing! Let me have a look at your file.")
        try:
            st.session_state.mydf = pd.read_csv(st.session_state[somekey], low_memory=False)
            st.dataframe(st.session_state.mydf)
        except:
            pass

if st.session_state.mydf.shape[0] == 0:
    button1 = st.button("Let's get started!")

    if button1:
        user_csv = st.file_uploader("Upload your file here!", type="csv", key="somekey", on_change=UploaderCallBack, args=("somekey",))

    if st.session_state.mydf.shape[0] > 0:
        st.write("And let's do some other things too.")

Cheers

1 Like
4

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