Example of async slots with a network request

async_slot2.py

import math
import sys
import asyncio
from functools import partial

from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QGridLayout, QProgressBar
from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkRequest
from PyQt5.QtCore import QUrl

from quamash import QEventLoop


def async_reply(reply, signal='finished'):
    future = asyncio.Future()
    getattr(reply, signal).connect(lambda: future.set_result(None))
    return future

class MyWidget(QWidget):

    def __init__(self, parent=None):
        super().__init__(parent)
        layout = QGridLayout()
        self.nam = QNetworkAccessManager()

        self.pairs = []
        for i in range(10):
            b = QPushButton('Countdown: &%d' % i, clicked=partial(self.on_click, i))
            p = QProgressBar(visible=False)
            layout.addWidget(b, i, 0)
            layout.addWidget(p, i, 1)
            self.pairs.append((b, p))

        self.test_button = QPushButton('&test', clicked=self.on_test)
        layout.addWidget(self.test_button, i, 0)

        self.setLayout(layout)

    def on_test(self):
        asyncio.ensure_future(self._on_test())

    async def _on_test(self):
        self.test_button.setEnabled(False)
        print('getting')
        for i in range(30):
            await asyncio.sleep(.1)
            print('.', end='', flush=True)

        req = QNetworkRequest(QUrl('https://www.google.com'))
        reply = self.nam.get(req)
        await async_reply(reply)
        print('got', len(reply.readAll()), 'bytes')
        self.test_button.setEnabled(True)

    def on_click(self, i):
        asyncio.ensure_future(self._on_click(i))

    async def _on_click(self, i):
        b, p = self.pairs[i]
        b.setEnabled(False)
        p.setVisible(True)

        n = i * 100
        p.setMaximum(n)

        while n >= 0:

            await asyncio.sleep(0.01)

            p.setValue(n)
            b.setText('Countdown: %d' % math.ceil(n / 100))
            n -= 1

        b.setText('Countdown: &%d' % i)
        b.setEnabled(True)
        p.setVisible(False)


def main():
    app = QApplication(sys.argv)
    loop = QEventLoop(app)
    asyncio.set_event_loop(loop)  # NEW must set the event loop

    w = MyWidget()
    w.show()

    with loop:
        loop.run_forever()

if __name__ == '__main__':
    main()