Practical example how to use signals

[tisauro]

Hi,

I am using the library to list all WiFi networks available. I managed to do so but I cannot work out how to listen to the signal in order to detect when the scan is completed.
The documentation says: To know when the scan is finished, use the "PropertiesChanged" signal from "org.freedesktop.DBus.Properties" to listen to changes to the "LastScan" property.

I have tried several ways but none of them are working. Could you please provide an example to point me to the right direction?

Thank you in advance!

[igo95862]

Hello @tisauro

I have an example of listening to properties changed in this comment: python-sdbus/python-sdbus#63 (comment)

The example is for the BlueZ but it should work for NetworkManager once you replace the service name.

[tisauro]

thank you @igo95862

[igo95862]

Remember to have a variable that references the task that listens to the signals. Otherwise a dangling task will be garbage collected at some point.

[auspex]

I tried that myself looking just for disconnections, and got LOTS of signals, but none of them seemed very helpful. Both NetworkManagerSettings.connection_removed and NetworkConnectionSettings.removed look relevant, but they never seem to fire for me.

How can I know when my eth0 interface disconnects?

[igo95862]

Have you looked in to the NetworkManagerDeviceInterfaceAsync.state_changed signal?

First you need find path of the device you want to track. I think you can use NetworkManagerInterfaceAsync.get_device_by_ip_iface to get the device path by interfaces name.

After you have a path you can initialize a device proxy and start listening on the signal. It should look something like that:

async for x in NetworkDeviceWireless(eht0_path).state_changed.catch():
    print(x)

There are enums defined under sdbus_async.networkmanager.enums that you can use.

[igo95862]

I added example of listening on device state changes: https://github.com/python-sdbus/python-sdbus-networkmanager/blob/master/examples/2.0.0/async/listen-device-changes-async.py

@auspex do you find it useful?