Need help with updating text in Streamlit app

🎈 Using Streamlit
1

Hi everyone,

I’m currently having an issue with a piece of code that I’m working on in Streamlit. I’m trying to update the value of a text area based on some user input using a button, but I’m finding that I have to click the button twice in order for the text area to update.

Here’s the code that I’m using:

if "text" not in st.session_state:
    st.session_state["text"] = ""
text1 = st.text_area('Text : ', st.session_state["text"])
before = st.text_input('Before')
after = st.text_input('After')
button = st.button('Button')

if button:
    st.session_state["text"] = text1.replace(before, after)

Does anyone have any suggestions for how I might be able to fix this issue? I’m not sure what’s causing it, and I haven’t been able to find any solutions online so far.

Thanks in advance for any help you can provide!

2

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3

You are almost there. But when you click the button the script reruns immediately. So the same old text is displayed in the text_area, then st.button('Button') returns True and the text changes, but it is too late because it has already been displayed.

One way to solve this is using a callback instead of an if. Callbacks are called after the button is clicked and before the script reruns.

def replace_text():
    st.session_state["text"] = text1.replace(before, after)

if "text" not in st.session_state:
    st.session_state["text"] = ""
text1 = st.text_area('Text : ', st.session_state["text"])
before = st.text_input('Before')
after = st.text_input('After')
button = st.button('Button', on_click=replace_text)