Streamlit widget dependency

I am trying a simple concept of two widgets, where one is dependent on the other

I want to user to click a button, that opens up a number slider. The user then has the option to select the number through the number slider.

Here is the code I am using:

    import streamlit as st
    press_button = st.button("Press it Now!")
    if press_button :
        # ask for the value
        th = st.number_input("Please enter the values from 0 - 10",)

The issue I face is the moment I change the number slider’s value, streamlit reruns the entire thing, and one has to push the “button” again to get back to the number slider. Ultimately, the number slider never changes

Hello @fahadakbar,
Yeah, even I had to face problems like this. However, instead of using a button, I used a checkbox. The thing is - st.button() returns a boolean value ryt. So now only when it is true, it is going to display the st.number_input(). Therefore, when you enter a number, that press_button becomes false as you did not press it. That is why it happens.
Personally, I just used a checkbox and that solved the problem for me.
If there is a way around that without using checkbox, even I would love to know.
Anyways, try checkbox and see.

import streamlit as st
    press_button = st.checkbox("Press it Now!")
    if press_button :
        # ask for the value
        th = st.number_input("Please enter the values from 0 - 10",)

Regards,
Amaan

Thank you so much Amaan, this workaround was successful!

1 Like

This leaves me a question though,

when and why would you use a “button”?

:slight_smile:

@fahadakbar
There are many uses of st.button().

  1. Let’s say that you built a ML model and user inputs several fields. Then the user can press a button (‘Predict’) and your app can display the predicted output (st.success()).
  2. You want to visualize and after entering the fields, press (‘Visualize’) and so on.

Like this, there can be may combinations. It all depends on the architecture of your app i.e. how you want to use a specific widget or what you want to do with it etc. Hence, choose a component or widget based on the workflow of your app.

Cheers :+1:!
Amaan

@amaan_142

let’s say I have a predict button, and ask for the data from the user as an input
wouldn’t pressing the button means that the user will need to give me data again?

@fahadakbar
Check this example (Screenshots in the readme file). This is what I was talking about.

If you implement the session state or url get/set query parameters, you can maintain a “button pushed” flag which will allow you to persist the button pushed state across runs.