Question

I have to get event from COM API which has description:

HRESULT OnStatusMessage(
    [in] IDispatch* pStatusMessage
);

And IStatusMessage has properties: BSTR Description, LONG Code, etc.

My code doesn’t work:

import msvcrt
import pythoncom
from win32com.client import DispatchWithEvents

class evt(object):
    def OnConnectionLost(self):
        print 'method ConnectionLost'
    def OnStatusMessage(self, s):
        print 'method OnStatusMessage: '  + str(s.Description)
    def OnLogin(self, l):
        print 'method OnLogin:', l
    def OnMessage(self, msg):
    print 'method OnMessage'


session = DispatchWithEvents("NiApi.SrvrSession", evt)
# login settings....

session.Connect()

while 1:
    if msvcrt.kbhit():
    msvcrt.getch()
        session.Disconnect()
        break
    pythoncom.PumpWaitingMessages()

Module fails with traceback:

Traceback (most recent call last):
  File "C:\Python\AP_272\lib\site-packages\win32com\server\policy.py", line 277, in     _Invoke_
    return self._invoke_(dispid, lcid, wFlags, args)
  File "C:\Python\AP_272\lib\site-packages\win32com\server\policy.py", line 282, in _invoke_
    return S_OK, -1, self._invokeex_(dispid, lcid, wFlags, args, None, None)
  File "C:\Python\AP_272\lib\site-packages\win32com\server\policy.py", line 585, in _invokeex_
    return func(*args)
  File "d:\niapi.py", line 13, in OnStatusMessage
    print 'method OnStatusMessage' + str(s.Description)
AttributeError: 'PyIDispatch' object has no attribute 'Description'
pythoncom error: Python error invoking COM method.

Why i cant get this attribute?

Answer 1

I’ve found the answer here:

Need to dispatch this object:

message = Dispatch(s)
print 'method OnStatusMessage', str(message.Description)

And don’t forget to import Dispatch

from win32com.client import Dispatch