python - How can multiple buttons in Streamlit call the same Playwright page object? - Stack Overflow

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My operating environment is:

• Windows 11, Python 3.13
• Streamlit = 1.41.1
• Playwright = 1.49.1

Now, using Streamlit, I need to create three buttons. When the first button is pressed, it should use Playwright to open a web page in the browser. When the second button is pressed, it should use Playwright to take a screenshot of the web page. When the third button is pressed, it should use Playwright to close the window.

The problem I encounter is how to call the same page object when the GUI is re-run. Here is my code:

import streamlit as st
from playwright.async_api import async_playwright
import asyncio
import nest_asyncio
# apply nest_asyncio
nest_asyncio.apply()
# switch to ProactorEventLoop
if st.runtime.exists():
    asyncio.set_event_loop_policy(asyncio.WindowsProactorEventLoopPolicy())

# initialize session_state
if "browser" not in st.session_state:
    st.session_state.browser = None
if "page" not in st.session_state:
    st.session_state.page = None

async def open_browser():
    playwright = await async_playwright().start()
    st.session_state.browser = await playwright.chromium.launch(headless=False)
    st.session_state.page = await st.session_state.browser.new_page()
    await st.session_state.page.goto(";)
    st.success("webpage opened")

async def take_screenshot():
    if st.session_state.page:
        await st.session_state.page.screenshot(path="screenshot.png")
        st.success("snapshot saved as screenshot.png")
    else:
        st.error("please open the webpage first")

async def close_browser():
    if st.session_state.browser:
        await st.session_state.browser.close()
        st.session_state.browser = None
        st.session_state.page = None
        st.success("browser closed")
    else:
        st.error("browser not opened")

# Streamlit gui
st.title("Playwright and Streamlit integration")

if st.button("open"):
    asyncio.run(open_browser())

if st.button("snapshot"):
    asyncio.run(take_screenshot())

if st.button("close"):
    asyncio.run(close_browser())

When I run the code, after click the “open” button, the target page opened as expected, but when I click the “snapshot” button, the streamlit page keeps “running” without any error printing!

I am not familiar with Python Asyncio.

For the 3 designed button, I expect:

1. click btn "open", the target webpage opened, this has been achieved
2. then, click btn "snapshot", it will take snapshot for the target webpage, this blocked
3. then click btn "close", it will close the target webpage.

How can I fix this behavior?

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