[python-win32] Problem with COM Interface. Windows Installer

[Peter Mott]

The COM inteface apparently breaks when attempting to use "record" objects
derived from Windows.Installer.

Below is a sample script with comments:


import win32com.client
import os
import sys

msiOpenDatabaseModeReadOnly=0
msidb = "sample.msi"


installer = win32com.client.Dispatch("WindowsInstaller.Installer")
database = installer.OpenDatabase(msidb, msiOpenDatabaseModeReadOnly)
view = database.OpenView("SELECT File, FileName FROM File")
view.Execute()
record = view.Fetch()
x = record.FieldCount
print "%d fields" % x

# Everything to this point is fine. The print statement prints '2' as it
# should


# (1) This does not work. Trace follows:
x = record.DataSize(1)

#	Attempting to get the DataSize gets this error.
##Traceback (most recent call last):
##  File "C:\home\clients\SIMproject\SIM_INSTALL\BuildScripts\testinst.py", line
17, in -toplevel-
##    x = record.DataSize(1)
##  File "<COMObject <unknown>>", line 2, in DataSize
##com_error: (-2147352573, 'Member not found.', None, None)

# (2) This does not work with trace following
x = record.StringData(1)

##
##Traceback (most recent call last):
##  File "C:\home\clients\SIMproject\SIM_INSTALL\BuildScripts\testinst.py", line
14, in -toplevel-
##    x = record.StringData(1)
##  File "<COMObject <unknown>>", line 2, in StringData
##com_error: (-2147352573, 'Member not found.', None, None)

-----------------
These lines are from a corresponding  vbscript which works without
problem.

  fileId = record.stringData(1)
  filename= record.stringData(2)

I'm using W2K  version 5.00. Python is 2.3.1 and w32all is build 157. The same
problem is on 155. Windows Installer is version 2.00.2600.1183.

I traced some of the Python code. It tries to find out what sort of 'object' it
is looking for, can't, tries a method as a last resort but enjoys no success.

I certainly do not know enough about COM to make any headway with this.

Thanks for any help

Peter