Getting a dbus interface property using gdbus

[chimosky (Ibiam Chihurumnaya)]

I’m trying to get properties that’s been set on an interface and nothing I’ve tried seems to work.

This is how I’m trying to access the property;

 result = g_dbus_connection_call_sync (connection,
                                       name,
                                       "/org/gtk/GDBus/TestObject",
                                       "org.gtk.GDBus.TestInterface",
                                       "Get",
                                       g_variant_new ("(s)",
                                                      "WritingAlwaysThrowsError"),
                                       G_VARIANT_TYPE("(s)"),
                                       G_DBUS_CALL_FLAGS_NONE,
                                       -1,
                                       NULL,
                                       &error);

I get this error;

**
ERROR:gdbus-example-property.c:56:on_name_appeared: assertion failed (error == NULL): GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such method ?Get? (g-dbus-error-quark, 19)
Bail out! ERROR:gdbus-example-property.c:56:on_name_appeared: assertion failed (error == NULL): GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such method ?Get? (g-dbus-error-quark, 19)
Aborted (core dumped)

The server has the get_property callback set for the interface but that doesn’t seem to get called, I wrote an implementation for the “Get” method, and that also throws the same error.

[pwithnall (Philip Withnall)]

Use the org.freedesktop.DBus.Properties interface, not the org.gtk.GDBus.TestInterface.

[chimosky (Ibiam Chihurumnaya)]

When I use that interface, I get this error;

ERROR:gdbus-example-property.c:38:on_name_appeared:
assertion failed (error == NULL): GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod:
No such interface ?org.freedesktop.DBus.Properties? on object at
path /org/gtk/GDBus/TestObject (g-dbus-error-quark, 19)
Bail out! ERROR:gdbus-example-property.c:38:on_name_appeared:
assertion failed (error == NULL): GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod:
No such interface ?org.freedesktop.DBus.Properties? on object at path
/org/gtk/GDBus/TestObject (g-dbus-error-quark, 19)

Which seems a bit strange because the server can also emit on that interface from the same bus name.

[pwithnall (Philip Withnall)]

Use D-Spy to look at the server and check that it’s exporting the right interfaces.

[chimosky (Ibiam Chihurumnaya)]

This was very helpful, the server was exporting the right interfaces but I was passing the wrong arguments to the method, thank you!

This is the new method call;

  result = g_dbus_connection_call_sync (connection,
                                        name,
                                        "/org/gtk/GDBus/TestObject",
                                        "org.freedesktop.DBus.Properties",
                                        "Get",
                                        g_variant_new ("(ss)",
                                                       "org.gtk.GDBus.TestInterface",
                                                       "WritingAlwaysThrowsError"),
                                        G_VARIANT_TYPE("(v)"),
                                        G_DBUS_CALL_FLAGS_NONE,
                                        -1,
                                        NULL,
                                        &error);