[feature request] auto-load app when running the app, and auto-refresh when changing the code

[PrashantSaikia]

I have built a webapp which runs like so:

pywebio.start_server(app, port=8080, debug=True)

But when I run the code, it does not automatically open the app in the browser; I need to manually type the address in the browser and run it.

Also, when I change my code while the app is running, it does not auto-refresh the webpage, and I need to refresh it manually.

Is there a way to do these already? If not, it would be a nice thing to add.

[wang0618]

I will later add an API to register a callback function to webpage when it loses the connection.

With this API, you can register a page reload callback, and the page will reload when your app reload (the current connection will closed when app reload).

Another scenario for this API is: Sometimes, you may want to run a long-running application, such as a data dashboard placed in a public space. To prevent the application from accidentally disconnecting from the server due to network reasons and not being able to update the data in real time. The application can use this API to register a page realod callback function to refresh the page in this case

[PrashantSaikia]

@wang0618 Thanks for the prompt response!

I have one more question, although its not related to this topic. In my web app, when I deploy it in a web server (heroku), I get the following error message appearing for 1 second, and then the app hangs: "an internal error occurred in the application"

I don't get this error message when running the app locally. Any idea why that is or how to fix it? I have described the issues I have been facing when deploying my web app here, in case it helps in understanding why the error occurs.

[wang0618]

"an internal error occurred in the application" means that an exception is thrown in your application code. You can open the console panel of webbroswer to see the trackback of the exception.

BTW: Is the language of your webbroswer Chinese? It looks like you are an English-speaking user, pywebio should have displayed the English prompt.

[wang0618]

About the Chinese prompt: I found I miss a translation for this. I will fix it later.

[PrashantSaikia]

I am an English speaker, and my web browser is in English. But I got the error prompt in Chinese. So I used google translate to see what it means in English, and pasted it here.

[wang0618]

I am an English speaker, and my web browser is in English. But I got the error prompt in Chinese. So I used google translate to see what it means in English, and pasted it here.

Fixed this issue on 32f6feb

[wang0618]

Now, with the latest stable verion, you can use this decorator to make page refresh when the server restart:

import pywebio
from functools import wraps

def auto_refresh(app):
    @wraps(app)
    def inner():
        pywebio.session.run_js('WebIO._state.CurrentSession.on_session_close(()=>{setTimeout(()=>location.reload(), 1000)})')
        app()
        pywebio.session.hold()
    return inner

Usage of the decorator is:

@auto_refresh
def main():
    put_text('hello')

start_server(main, port=8080, debug=True)  # need to enable debug

[wang0618]

You can pass auto_open_webbrowser=True to start_server() to enable auto open web browser when server is started