I'm having difficulty understanding exactly how
DispatchWithEvents operates. I need to execute SQL
statements on tables in an Oracle database (using ADO)
and it runs fine when using Dispatch. However when I
include DispatchWithEvents both the Execute() and
Close() methods no longer work for my Dispatch object,
with a "Member not found" error appearing. Why does
Execute and Close work with Dispatch by itself but not
when DispatchWithEvents is added?
What I find interesting is that both the
ConnectComplete and ExecuteComplete functions appear
to fire in my events class, even though my error
appears in the Execute() statement.
We've noticed that Python can get ahead of the
execution of the SQL statements, such as adding a new
field and then attempting to calculate its value for
the records before Oracle has finished created it. Is
using DispatchWithEvents and waiting for the
ExecuteComplete (with pythoncom.PumpWaitingMessage)
the right solution?
CODE:
-----------------
from win32com.client import Dispatch,
DispatchWithEvents
class clsAdoEvents:
def OnWillConnect(self, str, user, pw, opt, sts,
cn):
pass
def OnConnectComplete(self, error, status,
connection):
print "Connection complete"
def OnExecuteComplete(self, lngRecordsAffected,
pError, adStatus, pCommand, pRecordset, pConnection):
print "Statement executed"
objAdoConnection= Dispatch('ADODB.Connection')
objAdoConnectionEvents=
DispatchWithEvents(objAdoConnection, clsAdoEvents)
objAdoConnection.ConnectionString =
"Provider=MSDAORA;Password=pwd;User ID=user;Data
Source=server"
objAdoConnection.Open()
objAdoConnection.Execute("UPDATE streams SET test=99")
objAdoConnection.Close()
del objAdoConnection
---------------------
OUTPUT:
---------------------
Connection complete
Statement executed
Traceback (most recent call last):
File
"C:\Python24\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py",
line 310, in RunScript
exec codeObject in __main__.__dict__
File
"C:\bposthumus\programming\Python\PythonExamples\sqlWithEvents.py",
line 17, in ?
objAdoConnection.Execute("UPDATE streams SET
test=99")
File
"C:\Python24\lib\site-packages\win32com\gen_py\2A75196C-D9EB-4129-B803-931327F72D5Cx0x2x8.py",
line 2064, in Execute
, RecordsAffected, Options)
File
"C:\Python24\Lib\site-packages\win32com\client\__init__.py",
line 446, in _ApplyTypes_
return self._get_good_object_(
com_error: (-2147352567, 'Exception occurred.', (0,
None, 'Member not found.', None, 0, -2147352573),
None)
--------------------
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