Dynamics GP eConnect and handling exceptions under Web API

Beware when using eConnect with ASP.NET Web API.

slipping 

… as exceptions raised by eConnect will not be of type eConnect.Exception

thus using our normal typical catch block, such as:

catch(eConnectException ex)

will not work, because all eConnectExceptions will actually cause the following exception to be raised/returned:

System.NullReferenceException: Object reference not set to an instance of an object.

  at Microsoft.Dynamics.GP.eConnect.EventLogHelper.AddExceptionHeader(String action, Object[] inputParameters, StringBuilder errorString)

This is because there is a flaw in the eConnect, eConnect.EventLogHelper.CreateEventLogEntry method. It attempts to extract the Thread.CurrentPrincipal.Identity.Name as part of the output, but when eConnect is used in the context of ASP.NET Web API, this is null

As it is null this causes a new exception to be caused, the original exception superseded by the new System.NullReferenceException caused in the exception handler, that masks the original issue.

Explicitly setting the current threads identity name just before calling eConnect solves this problem and so allows the eConnect.Exception to be caught and processed as would normally be expected.

I discovered this whilst diagnosing a problem on the forums for someone, see: Econnect Exception Handling doesn't work in WEB API 2 application

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