topic What's wrong in my code? If you can help? in ArcObjects SDK Questions

What's wrong in my code? If you can help?

ShaningYu — Thu, 26 Sep 2013 15:14:59 GMT

See my code below:
            // fc - a feature class w/ multiple feature records
            ESRI.ArcGIS.Location.RouteEventSourceClass rteEventSourceClass;
            rteEventSourceClass = fc as ESRI.ArcGIS.Location.RouteEventSourceClass;
But the value of the rteEventSourceClass is null. Did I do something wrong? I want to retrieve the rteEventSourceClass values. Thanks.

Re: What's wrong in my code? If you can help?

ShaningYu — Thu, 26 Sep 2013 16:31:06 GMT

From the ArcObjects diagram (http://help.arcgis.com/en/sdk/10.0/arcobjects_net/componenthelp/index.html#//003100000138000000), it is known that the ESRI.ArcGIS.Location.RouteEventSourceClass is a sub-class of FeatureClass. In this piece of code below:
ESRI.ArcGIS.Location.RouteEventSourceClass rtEvtSourceClass = (ESRI.ArcGIS.Location.RouteEventSourceClass)fc;
// fc - a feature class
Got InvalidCastException: Unable to cast COM object of type 'System.__ComObject' to class type 'ESRI.ArcGIS.Location.RouteEventSourceClass'. COM components that enter the CLR and do not support IProvideClassInfo or that do not have any interop assembly registered will be wrapped in the __ComObject type. Instances of this type cannot be cast to any other class; however they can be cast to interfaces as long as the underlying COM component supports.
Why can't cast here? Thanks.

Re: What's wrong in my code? If you can help?

ShaningYu — Thu, 26 Sep 2013 17:36:05 GMT

As the continuation of 2nd post of the thread, I followed the recommendation in the error message, used interface and then did the casting, like that:
ESRI.ArcGIS.Location.IRouteEventSource rtEvtSourceClass;
rtEvtSourceClass = (ESRI.ArcGIS.Location.IRouteEventSource)fc;
Then, got new error: Unable to cast COM object of type 'System.__ComObject' to interface type 'ESRI.ArcGIS.Location.IRouteEventSource'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{641755F0-B7DE-11D3-9F7C-00C04F6BDF06}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).
Then, I opened the Registry Editor to search the {641755F0-B7DE-11D3-9F7C-00C04F6BDF06}. The result shows that it is at
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Wow6432Node\Interface\.
For the 'No such interface supported ...', I referred to http://www.huggill.com/2012/09/06/solving-an-exception-occurred-in-publishing-no-such-interface-supported-exception-from-hresult-0x80004002-e_nointerface-with-visual-studio-2012-rc/ provided procedure:
1. Run Command Prompt as Administrator
2. regsvr32 actxprxy.dll
3. Restart Visual Studio
The problem is still there and the error message is the same. What I should do next? Welcome your suggestion or hint. Thanks.

Re: What's wrong in my code? If you can help?

Anonymous User — Thu, 26 Sep 2013 18:40:42 GMT

Make sure your reference to fc is also an interface rather than a class.

While .NET technically supports 'class casting', to ease the transition from VB6, you'll run into all sorts of problems with ArcObjects and COM interop.

Re: What's wrong in my code? If you can help?

ShaningYu — Fri, 27 Sep 2013 18:06:18 GMT

The cast posted before was not correct. In stead of
ESRI.ArcGIS.Location.IRouteEventSource rtEvtSourceClass;
rtEvtSourceClass = (ESRI.ArcGIS.Location.IRouteEventSource)fc;
It should be
IFeatureClass fc = (IFeatureClass)rtEvtSourceClass;
Thread is to be closed.