Vacuum position returns empty string.

[v4m3rrr]

Describe the bug
When running the following command:

miiocli -d genericmiot --ip 192.168.1.128 --token XXXXXXX --model xiaomi.vacuum.d109gl get_property_by 10 4

The output is:

[{'did': '1140560657', 'ssid': 10, 'piid': 4, 'code': 0, 'value': ''}]

The property with ssid=10 and piid=4 corresponds to the vacuum's position (vacuum-position). However, the returned value is an empty string.

Version Information

• OS: Debian GNU/Linux 12 (Bookworm) on Raspberry Pi 5
• python-miio version: 0.6.0.dev0

Device Information

• Model: xiaomi.vacuum.d109gl
• Hardware version: Linux
• Firmware version: 4.5.6_0376

To Reproduce
Steps to reproduce the issue:

1. Run the command:

   miiocli -d genericmiot --ip 192.168.1.128 --token XXXXXXX --model xiaomi.vacuum.d109gl get_property_by 10 4
   

Expected Behavior
The command should return a meaningful value for the vacuum-position property instead of an empty string.

Console output

Running command get_property_by
DEBUG:miio.miioprotocol:Got a response: Container:
    data = Container:
        data = b'' (total 0)
        value = b'' (total 0)
        offset1 = 32
        offset2 = 32
        length = 0
    header = Container:
        data = b'!1\x00 \x00\x00\x00\x00C\xfb\x93\x11\x00\x06\x93f' (total 16)
        value = Container:
            length = 32
            unknown = 0
            device_id = unhexlify('43fb9311')
            ts = 1970-01-05 23:42:30+00:00
        offset1 = 0
        offset2 = 16
        length = 16
    checksum = b'\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff' (total 16)
DEBUG:miio.miioprotocol:Discovered 43fb9311 with ts: 1970-01-05 23:42:30+00:00, token: b'ffffffffffffffffffffffffffffffff'
DEBUG:miio.miioprotocol:192.168.1.128:54321 >>: {'id': 1,
 'method': 'get_properties',
 'params': [{'did': '10-4', 'piid': 4, 'siid': 10}]}
DEBUG:miio.miioprotocol:192.168.1.128:54321 (ts: 1970-01-05 23:42:30+00:00, id: 1) << {'exe_time': 12,
 'id': 1,
 'result': [{'code': 0,
             'did': '1140560657',
             'piid': 4,
             'siid': 10,
             'value': ''}]}
[{'did': '1140560657', 'siid': 10, 'piid': 4, 'code': 0, 'value': ''}]

[rytilahti]

Unfortunately, there is nothing this library can do if the device doesn't respond with any data. Maybe there is a separate call that needs to be executed before that data can be read, or maybe that data is only available when the device is in a specific mode (e.g., cleaning)?