On_change

🎈 Using Streamlit
1

Hello,

I see there is a possibility to use the on_change keyword on some widgets:

Widgets which support the on_change event:
• st.checkbox
• st.color_picker
• st.date_input
• st.multiselect
• st.number_input
• st.radio
• st.select_slider
• st.selectbox

and in particular the selectbox widget. But when I try to use it, even with the default value which is None, there is an error:

TypeError: selectbox() got an unexpected keyword argument 'on_change'

Why is that ?

Thank you

2

Hmm I just noticed that I didn’t have the latest version of Streamlit that’s why …

1 Like
3

I’ve just stumbled upon this new on_change feature for text_input but I can’t figure out how to use it. Can you share how you managed to get it to work?

4

Hello,

If you install the latest version of Streamlit:
pip install --upgrade streamlit

You will be able to make the on_change event work .

I don’t remember if text_input has this behavior possible but if it has , with the latest version of Streamlit it should work I guess

Edit: yes on_change is available for text_input
Here is the full list:

https://docs.streamlit.io/en/latest/session_state_api.html