[Ironpython-users] Linq exception, only when debugging

Nicholas Devenish misnomer at gmail.com
Mon Nov 19 00:39:03 CET 2012

I've come across a new error in my quest to use sqlalchemy; When running a query, I get the exception:

      Unable to cast object of type 'System.Linq.Expressions.FieldExpression' to type 'System.Linq.Expressions.BlockExpression'.

The debugger launches to a line that passes along the results object, but I haven't narrowed this exactly - it seems to be some interaction with the SQLite module. 

The strange thing is, this only happens when running with PTVS (2012) with the debugger attached - If I explicitly ask it to run without attaching, this problem doesn't seem to happen, and indeed runs the query fine.

Any ideas why I would be getting the difference wrt debugging?

Thanks all,


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