Asyncio | How to resolve "a coroutine was expected" error?

Question

I grabed the two_devices.py code example from here: https://github.com/hbldh/bleak/blob/develop/examples/two_devices.py

When I try to execute it, I receive the following error:

Exception has occurred: ValueError
a coroutine was expected, got <_GatheringFuture pending>
  File "path to file", line 39, in <module>
    "F0CBEBD3-299B-4139-A9FC-44618C720157",
ValueError: a coroutine was expected, got <_GatheringFuture pending>

Can anyone provide some suggestions how to resolve this?

Answer 1

The linked code is incorrect. It's calling a synchronous function with asyncio.run, and it's never await-ing on asyncio.gather (and you can't use await in a synchronous function).

A correct implementation would look something like this:

...

async def main():
    return await asyncio.gather(*(connect_to_device(address)
                                  for address in addresses))

if __name__ == '__main__':
    asyncio.run(
        main(
            [
                "B9EA5233-37EF-4DD6-87A8-2A875E821C46",
                "F0CBEBD3-299B-4139-A9FC-44618C720157",
            ]
        )
    )

---

This is still problematic -- it will run, but the code never does anything with the return value from main.