Can you retrieve a D-Bus property without calling org.freedesktop.DBus.Properties.Get? - dbus

Question

Say I want to programmatically get the interface name of my ethernet card. This seems to work:
dbus-send --print-reply \
--type=method_call \
--system \
--dest=org.freedesktop.NetworkManager \
/org/freedesktop/NetworkManager/Devices/0 \
org.freedesktop.DBus.Properties.Get \
string:org.freedesktop.NetworkManager.Device \
string:Interface
Which returns:
method return sender=:1.5 -> dest=:1.135 reply_serial=2
variant string "eth0"
Is there some way of cutting out the middleman org.freedesktop.DBus.Properties.Get and retrieve the property more directly? Alas, calling it as a method does not work:
dbus-send --print-reply \
--type=method_call \
--system \
--dest=org.freedesktop.NetworkManager \
/org/freedesktop/NetworkManager/Devices/0 \
org.freedesktop.NetworkManager.Device.Interface
Returns:
Error org.freedesktop.DBus.Error.UnknownMethod:
Method "Interface" with signature "" on interface
"org.freedesktop.NetworkManager.Device" doesn't exist
I ask because having to call org.freedesktop.DBus.Properties.Get looks like having to call a object.getProp("someproperty") instead of object.getSomeProperty() in Python/Java/etc.

Answer 1

Yep, you can do that if you use qdbus. I don't have NetworkManager with me, but a command like that should work:
qdbus --system \
org.freedesktop.NetworkManager \
/org/freedesktop/NetworkManager/Devices/0 \
org.freedesktop.NetworkManager.Device.Interface
There are various command-line clients for talking to D-Bus, some are more convenient than others. Here's the list of the ones I know.
dbus-send (provided with D-Bus itself)
gdbus (provided by GLib)
qdbus (provided by Qt)
busctl (provided by systemd)

Answer 2

No.
Most likely org.freedesktop.DBus.Properties.GetAll will return you same value, but internally every service implement properties as handlers to messages with org.freedesktop.DBus.Properties.Get/org.freedesktop.DBus.Properties.GetAll method calls.
It looks like object.getProp("someproperty") because it actually is more like this pseudo-code
bus.handleMessage({
service: "org.freedesktop.NetworkManager",
object: "/org/freedesktop/NetworkManager/Devices/0",
iface: "org.freedesktop.NetworkManager.Device.Interface",
body: [ "org.freedesktop.NetworkManager.Device", "Interface"],
thisMessageIsReplyTo: null
})
Internally every method call/signal/reply is just a message with big signature (service name/object path/interface) and body