[PyQt] Passsing Unsigned Int to DBus

[Phil Thompson]

On 10 Feb 2019, at 5:55 pm, Bo Møller Petersen <kemibo at gmail.com> wrote:
> 
> I'm trying to use PyQt5's DBus module to interact with the KDE PowerManagerAgent on a linux system. When calling the AddInhibition method I need to send the first paramter as an uint32 (Unsigned int), but the code sends the value as a singed int.
> 
> The code is written using Python 3 and using Pyqt5
> 
> class PowerChangeInhibitor:
>     def __init__(self):
>         self.dBusService = 'org.kde.Solid.PowerManagement.PolicyAgent'
>         self.dBusPath = '/org/kde/Solid/PowerManagement/PolicyAgent'
>         self.dBusInterface = 'org.kde.Solid.PowerManagement.PolicyAgent'
>         self.cookies = []
>         
>     def ActivateInhibition(self, interruptSession, changeProfile, changeScreenSettings,who, reason):
> 
>         
>         self.dBus = QtDBus.QDBusConnection.sessionBus()
>         if interruptSession:
>             #dBusInterface = QtDBus.QDBusInterface(self.dBusService, self.dBusPath,'' , self.dBus) 
>             #reply = dBusInterface.call('AddInhibition',1,who,reason)
>             
>             msg = QtDBus.QDBusMessage.createMethodCall(self.dBusService, self.dBusPath,self.dBusInterface,'AddInhibition')
>  
>             #unsignedValue = 1                                                   # writes 1 but typed as int32
>             #unsignedValue = ctypes.c_uint(1)                                    # Type not registered 
>             #unsignedValue = struct.unpack_from("I", struct.pack("i", 1))        # Type not registered
>             #unsignedValue = QtCore.QByteArray(b'0x01')[0]                       # Type not registered 
>             #unsignedValue =  bytes(1)                                           # Type not registered
>             #unsignedValue = QtDBus.QDBusVariant(1)                              # array of bytes "0x01"
>             #unsignedValue = QtDBus.QDBusVariant(1)[0]                           # QDBusVariant does not support indexing
>             #unsignedValue = QtDBus.QDBusVariant().setVariant(ctypes.c_uint(1))  # Variant contained QVariantInvalid
>             unsignedValue =  QtDBus.QDBusVariant(ctypes.c_uint(1))                # Type not registered
> 
>             msg << unsignedValue << who << reason
>             reply = QtDBus.QDBusReply(self.dBus.call(msg))
>             if reply.isValid():
>                 self.cookies.append(reply.value())
> 
>   
> I have commented out previous attempts with their results on the right. Using dbus-monitor I can see that the part where i'm struggeling is getting QDBusInterface to emit the desired UNIT32 type info.
> 
> Any pointers on how I pass an unsigned int as an argument to my QDBusMessage ?

Use QVariant.convert()...

qvar = QVariant(ctypes.c_uint(1))
qvar.convert(QVariant.UInt)
unsignedValue = QtDBus.QDBusVariant(qvar)

Phil