Patch for QueryTranslator Invalid Cast to object array

Hello NHibernate developers,

there seems to be an issue with a hard cast in the QueryTranslator 
class, line 1452 (trunk) - resp. line 1288 (1.2.1) ...

The hard cast in method GetResultList to an object[] fails in the case 
of my company's product, when using an IResultTransformer.

I chose to use an IResultTransformer implementation for Criteria's and 
Query's to be able to set a required property. It seems an appropriate 
way to me and my tests (and the running app) ensure that it works.

However, I had to patch the QueryTranslator at the locations mentioned 
above, because it threw an invalid cast exception (stacktrace below) - 
because the IList of my objects could not be casted to an object[]. 
Debugging it, showed me that the "results" list contained my domain 
objects, but it could not be casted to an object[]. It was a collection 
of my domain types and my domain types are no object[]. Now, some time 
passed by since then, and our product works fine with the patch, so 
unfortunately I forgot the exact reason, but I'd guess, I used the 
generic Query signature and so the results list was a generic list that 
cannot be casted to object[]. But also ArrayList or Hashtable cannot be 
casted to object[]...

A little experiment, gave me the compiler error:

Cannot convert type 
'System.Collections.Generic.List<ConsoleApplication1.Project>' to 'object[]'

class Program
{
	static void Main(string[] args)
	{
		List<Project> projects = new List<Project>();
		object[] objs = (object[]) projects;
	}

	class Project {	}
}

=> same thing doesn't work with ArrayList or Hashtable ...


----
The code snippet from QueryTranslator in question:


	for (int i = 0; i < results.Count; i++)
	{
		object[] row = (object[]) results[i];
		results[i] = holderInstantiator.Instantiate(row);
	}

----
Patch - with a "safe" cast:

	object[] row = results[i] as object[];
	if (row != null)
	{
		results[i] = holderInstantiator.Instantiate(row);
	}



The included patch is for the NHibernate 2.0 trunk.
The same problem exists in earlier versions, namely 1.2.

I might be totally missing the root of the problem, but please excuse 
this, as I am not familiar with the NHibernate internals, but tried to 
apply a patch at the right place to enable the very useful feature of 
the IResultTransformer to our case - and maybe to others in future.


Here is the stacktrace:  (version 1.2.1)

    at NHibernate.Hql.Classic.QueryTranslator.GetResultList(IList 
results, IResultTransformer resultTransformer) in 
d:\dev\yap\nhibernate\trunk\src\NHibernate\Hql\Classic\QueryTranslator.cs:line 
1291
    at NHibernate.Loader.Loader.ListIgnoreQueryCache(ISessionImplementor 
session, QueryParameters queryParameters) in 
d:\dev\yap\nhibernate\trunk\src\NHibernate\Loader\Loader.cs:line 1744
    at NHibernate.Loader.Loader.List(ISessionImplementor session, 
QueryParameters queryParameters, ISet querySpaces, IType[] resultTypes) 
in d:\dev\yap\nhibernate\trunk\src\NHibernate\Loader\Loader.cs:line 1738
    at NHibernate.Hql.Classic.QueryTranslator.List(ISessionImplementor 
session, QueryParameters queryParameters) in 
d:\dev\yap\nhibernate\trunk\src\NHibernate\Hql\Classic\QueryTranslator.cs:line 
1124
    at NHibernate.Impl.SessionImpl.Find(String query, QueryParameters 
parameters, IList results) in 
d:\dev\yap\nhibernate\trunk\src\NHibernate\Impl\SessionImpl.cs:line 1763



Hope to could have helped a bit ...
Nevertheless, big thanx for such a great software!

... best regards,

Stefan


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Index: QueryTranslator.cs
===================================================================
--- QueryTranslator.cs	(revision 3539)
+++ QueryTranslator.cs	(working copy)
@@ -1449,8 +1449,11 @@
 			{
 				for (int i = 0; i < results.Count; i++)
 				{
-					object[] row = (object[]) results[i];
-					results[i] = holderInstantiator.Instantiate(row);
+					object[] row = results[i] as object[];
+					if (row != null)
+					{
+						results[i] = holderInstantiator.Instantiate(row);
+					}
 				}
 
 				if (holderConstructor == null && resultTransformer != null)