I'm using a custom named query with NHibernate which I want to return a collection of Person objects. The Person object is not mapped with an NHibernate mapping which means I'm getting the following exception:
System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
It's getting thrown when the Session gets created because it can't find the class name when it calls NHibernate.Cfg.Mappings.GetClass(String className). This is all fairly understandable but I was wondering if there was any way to tell NHibernate to use the class even though I haven't got a mapping for it?
To solve this, I ended up using the TupleToPropertyResultTransformer and providing the list of property values. There are a few limitations to this, the main one being that the SQL query must return the results in the same order as you provide your properties to the TupleToPropertyResultTransformer constructor.
Also the property types are inferred so you need to be careful with decimal columns returning only integer values etc. Apart from that using the TupleToPropertyResultTransformer provided a reasonably easy way to use an SQL query to return a collection of objects without explicitly mapping the objects within NHibernate.