QNetworkAccessManager finished.connect never called

[Tyskie]

Hello everyone,
I have a weird situation where my QNetworkAccessManager's finished slot is never triggering the callback...it drives me crazy :D
Maybe one of you see what I am missing?

here is the code:

import sys
from PyQt5.QtWidgets import QApplication
from PyQt5.QtCore import QUrl
from PyQt5.QtWidgets import QWidget
from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkRequest


class ImageGetter:
    def __init__(self, callback, url, params):
        self.url = url
        self.callback = callback
        self.params = params

    def from_url(self):
        manager = QNetworkAccessManager()
        request = QNetworkRequest(QUrl(self.url))
        manager.finished.connect(self.dupa)
        manager.get(request)
        print('till here everything is fine')

    def dupa(self, reply):
        print('this is never called')
        logging.error(args)
        logging.error(kwargs)


def get_image_from_url(callback, url, **params):
    image_getter = ImageGetter(callback, url, params)
    image_getter.from_url()


def callback():
    raise NotImplementedError('reserved for future usage')


if __name__ == '__main__':

    app = QApplication(sys.argv)
    w = QWidget()
    w.show()
    get_image_from_url(
        callback,
        'https://cdn.discordapp.com/embed/avatars/3.png',
        identifier='def'
    )

    sys.exit(app.exec_())

the output:

(.pyvenv) D:\Workspace\private\discord_overlay>python test.py
till here everything is fine

[JonB]

@Tyskie
Your manager = QNetworkAccessManager() goes out of scope (Python destroys it) at the end of from_url() method. That's before the finished arrives. Objects like this must persist. You probably want to make a member variable of ImageGetter? But then the same may be happening to your image_getter in get_image_from_url()? Anyway, that's what you need to look at.

I don't understand why you have any Python global functions here. I would make everything, including slots, members of some class you instantiate.

[JonB]

@Tyskie
Your manager = QNetworkAccessManager() goes out of scope (Python destroys it) at the end of from_url() method. That's before the finished arrives. Objects like this must persist. You probably want to make a member variable of ImageGetter? But then the same may be happening to your image_getter in get_image_from_url()? Anyway, that's what you need to look at.

I don't understand why you have any Python global functions here. I would make everything, including slots, members of some class you instantiate.

[Tyskie]

Thanks for you answer, I think I see now I will try to keep it alive then
About the global functions they are in fact pretty deep in the code, but are attached to a class, that was just for simplicity.