CoreBluetooth: BleakClient(device_from_scan) fails with missing address_or_ble_device.metadata["delegate"]

[jeffsf]

(venv) [jeff@mini ~/devel/pyDE1]$ python --version
Python 3.9.5
(venv) [jeff@mini ~/devel/pyDE1]$ pip list
Package                        Version
------------------------------ -------
aiologger                      0.6.1
bleak                          0.11.0
pip                            21.0.1
pyobjc-core                    7.1
pyobjc-framework-Cocoa         7.1
pyobjc-framework-CoreBluetooth 7.1
pyobjc-framework-libdispatch   7.1
setuptools                     56.0.0

macOS 10.14.6

Description

Working toward being able to manage multiple devices without connectivity loss under Bluez (#361) and developing locally on my Mac, I found that trying to create a BleakClient from a BLEDevice returned from a scan failed. I expected that the BLEDevice passed to the scanner callback is_skale(device: BLEDevice, adv: AdvertisementData) would be able to be used in skale = BleakClient(device). However, an error was reported under macOS (and not seen running Python 3.9.5 built for RPi Buster)

Traceback (most recent call last):
  File "/Volumes/miniup-users/jeff/devel/pyDE1/scale_direct.py", line 164, in is_skale
    skale = BleakClient(device)
  File "/Volumes/miniup-users/jeff/devel/pyDE1/venv/lib/python3.9/site-packages/bleak/backends/corebluetooth/client.py", line 51, in __init__
    self._central_manager_delegate = address_or_ble_device.metadata["delegate"]
KeyError: 'delegate'

What I Did

Examination of the device using a debugger suggests that the error is "correct" and that the device is of the proper class and at least partially populated

Running the same code remotely on the RPi does not trigger the error, though also has an empty metadata dict.

(pyDE1_3.9) jeff@pi-walnut:~ $ python --version
Python 3.9.5
(pyDE1_3.9) jeff@pi-walnut:~ $ pip list
Package    Version
---------- -------
bleak      0.11.0
dbus-next  0.2.2
pip        21.1.2
setuptools 56.0.0

Code To Replicate

Though tied to a specific device, I am more than willing to work to provide additional information as needed.

async def find_first_skale(timeout=5.0) -> BleakClient:

    scanner = BleakScanner(timeout=timeout)
    skale: Optional[BleakClient] = None
    found_skale = asyncio.Event()

    def is_skale(device: BLEDevice, adv: AdvertisementData):

        nonlocal skale

        if found_skale.is_set():
            logger.info(f"Skipping adv from {device} as already found skale")
            return
        if adv.local_name and adv.local_name.startswith('Skale'):
            found_skale.set()
            try:
                skale = BleakClient(device)
            except KeyError:
                logger.warning(
                    "Fallback to address on KeyError, "
                    "likely from metadata: {}\n{}".format(
                        device.metadata,
                        traceback.format_exc(),
                    ))
                skale = BleakClient(device.address)
            logger.info(f"Scale: {skale} at {skale.address}")

    scanner.register_detection_callback(is_skale)

    logger.info("Scan start")
    await scanner.start()

    logger.info("Waiting for Skale adv")
    try:
        await asyncio.wait_for(found_skale.wait(), timeout=timeout)
        logger.info("Found")
    except asyncio.TimeoutError:
        logger.info("Not found")

    await stop_scanner_if_running(scanner)
    return skale

In context:
scale_direct.py.gz

[dlech]

Duplicate of #448?

[jeffsf]

Closed as duplicate of #448

Thanks!