BUG: XL97 Errors Using OLE Automation (165273)
The information in this article applies to:
- Microsoft Visual C++ 2.0
- Microsoft Visual C++ 2.1
- Microsoft Visual C++ 2.2
- Microsoft Visual C++ 4.0
- Microsoft Visual C++ 4.0a
- Microsoft Visual C++ 4.1
- Microsoft Visual C++, 32-bit Enterprise Edition 4.2
- Microsoft Visual C++, 32-bit Enterprise Edition 5.0
- Microsoft Visual C++, 32-bit Enterprise Edition 4.2b
- Microsoft Visual C++, 32-bit Professional Edition 4.2
- Microsoft Visual C++, 32-bit Professional Edition 5.0
- Microsoft Visual C++, 32-bit Professional Edition 4.2b
This article was previously published under Q165273 SYMPTOMS
OLE Automation code that successfully controlled previous versions of
Microsoft Excel may fail with Microsoft Excel 97. If the code was
generated by a scripting language, you may get an error message similar to
the following:
Method does not exist
CAUSE
This problem can be caused by an improperly implemented OLE Automation
Controller. An OLE Automation Controller actually makes the calls to a
server application's IDispatch interface to allow that server to be
controlled by the client.
In this case, the problem relates to how the IDispatch::Invoke method is
called. The Invoke method requires that you specify the context of the
IDispatch call by passing one or more of the following flags via the
wFlags parameter:
- DISPATCH_METHOD
- DISPATCH_PROPERTYGET
- DISPATCH_PROPERTYPUT
- DISPATCH_PROPERTYPUTREF
These flags indicate whether the function being called via IDispatch should
be called as a property or a method.
Previous versions of Microsoft Excel implemented their collection accessor
functions as methods. For example, consider the following line of Visual
Basic For Applications, Excel edition code:
Workbooks(1).Worksheets(1).Range("A1").Value = 10
Workbooks, Worksheets, and Range are implemented as methods in Microsoft
Excel version 5.0 and 7.0. However, Microsoft Excel 97 implements these
same calls as properties.
If OLE Automation Controllers break when they try to drive Excel 97, it is usually because they are passing DISPATCH_METHOD as the
wFlags parameter of IDispatch::Invoke. Because these functions are no
longer implemented as methods in Microsoft Excel 97, the Invoke method
failS with DISP_E_MEMBERNOTFOUND. If you are using a scripting
language on top of the controller, you generally get an error message
similar to the one mentioned above.
RESOLUTION
To resolve this problem, modify the OLE Automation Controller code so that
calls to IDispatch::Invoke include DISPATCH_PROPERTYGET as part of the
wFlags parameter. Though you can pass DISPATCH_PROPERTYGET by itself where
these property calls are being made, the best solution is to logically OR
this flag with DISPATCH_METHOD (DISPATCH_PROPERTYGET | DISPATCH_METHOD).
By doing this, you ensure that the function call succeeds
regardless of whether it has been implemented as a property or a method.
It should be emphasized that this problem is not a problem in Microsoft
Excel. The problem lies in the implementation of the OLE Automation
Controller. The only solution to this problem is to fix the OLE Automation
Controller code.
Customers who did not write the OLE Automation Controller (such as those
who may be using a scripting language) should contact their vendor for
support.
To confirm that this is a problem in the controller code, Visual Basic
should be used to automate Microsoft Excel in the fashion attempted by the
non-functioning controller. If the Visual Basic test is successful, the
problem lies in the controller.
STATUSMicrosoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article. MORE INFORMATION
Developers who have used the Class Wizard in Visual C++ to
generate wrapper classes to automate Microsoft Excel may also encounter
this problem if they generated the classes from an older type library.
Class Wizard reads the type library and calls IDispatch::Invoke with
whichever flag is appropriate. When used with an older type library, it
sees that the collection accessors are implemented as methods, so it
uses the DISPATCH_METHOD flag when it calls these functions. The
solution is the same. Logically OR DISPATCH_METHOD with
DISPATCH_PROPERTYGET for the wFlags parameter in the Dispatch helper
function calls. This results in IDispatch::Invoke being properly
called by the wrapper classes.
REFERENCES
For additional information, please see the following:
"Ole2 Programmer's Reference," Volume 2, Chapter 5, "Dispatch Methods", p.
112
For additional information, please see the following article in the
Microsoft Knowledge Base:
141759
SAMPLE: XLCLIENT: Automation Client for Excel
| Modification Type: | Minor | Last Reviewed: | 3/9/2005 |
|---|
| Keywords: | kbbug kbinterop kbpending KB165273 |
|---|
|