[pywin32-bugs] [ pywin32-Bugs-1119908 ] CastTo/QueryInterface problem

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Bugs item #1119908, was opened at 2005-02-10 09:06
Message generated for change (Comment added) made by oleaw
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=551954&aid=1119908&group_id=78018

Category: win32
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: oleaw (oleaw)
Assigned to: Nobody/Anonymous (nobody)
Summary: CastTo/QueryInterface problem

Initial Comment:
In the COM API I am using, the following is provided: To 
create a new patient object I have to cast the Patient 
manager interface to the IDIContstructor interface. 

PatMgr: IDIPatientMgr;
NewPat: IDIPatient;
...
PatMgr := DISession.GetManagerById(miPatient) as 
IDIPatientMgr;
NewPat := (PatMgr as IDIConstructor).CreateNew as 
IDIPatient;
//edit the patient...
//Save the changes
(NewPat as IDIEdit).Save;


In python I have written the following code.

miPerson = 26        
try:
   PersonMgr
except NameError:
   PersonMgr = self.__dips_api.GetManagerById(miPerson)
else:
   print "PersonMgr eksisterer"
      
NewPerson = CastTo(PersonMgr, 'IDIPersonMgr')

This casts PersonMgr to the right Interface.
My problem is that once I use the CastTo function all of 
my other functions cease to work. Apparently all the 
objects are wrapped in PyIUnkown, and python is no 
longer able to find their appropriate type. This problem 
will persist until delete the automatically generated 
python COM code and restart IDLE.
All the interfaces I am using are IDispatch.

I have also tried to alternatively cast the interface with
PersonMgr.QueryObject(‘IDIConstructor’) and
Dispatch(PersonMgr , None, 'IDIContructor'), 
but these functions are unable to find the interface.
Have also tried with makepy

Can anyone provide information on how to make CastTo 
work, (can I unwrap the PyIUnknown wrapper?)


Ole A


----------------------------------------------------------------------

>Comment By: oleaw (oleaw)
Date: 2005-02-10 09:14

Message:
Logged In: YES 
user_id=1216110

The line 
NewPerson = CastTo(PersonMgr, 'IDIPersonMgr') 
is
NewPerson = CastTo(PersonMgr, 'IDIConstructor') 
and IDIContructor should be IDIConstructor

This however is not the problem

Ole A

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=551954&aid=1119908&group_id=78018