InvalidOperationException: This transformer is not initialized by Cached Query

[chrisredburnetail]

Between version 5.3.10 and 5.3.11 the behaviour of cached SQL Query results changed when using AliasToBean transform.

ISession session;
session.CreateSQLQuery("select 'REGIONCODE' as regionCode  ")
		.AddScalar("regionCode", NHibernateUtil.String)
		.SetResultTransformer(Transformers.AliasToBean<ResultDto>())
		.SetCacheable(true)
		.List();

This works the first time through when caching is enabled, but when run again it fails with a "System.InvalidOperationException : This transformer is not initialized" exception.

I've created the attached Test Case which gives the exception in the second call to .List in the GetCacheableSqlQueryResults method.

In my actual code the SELECT statement involves tables and join, etc - its been simplified for this test case to not include any entities.

GH3169.zip

[bahusoid]

Looks like #2943 is culprit. But then your cached query is not really retrieved from cache in 5.3.10 (See #2904)

[bahusoid]

So this issue was enabled by triggering correct caching in #2943. But the problem code introduced in #1489 (ping @fredericDelaporte)
The problem here is that auto discovery type queries fills part of query cache key only after query is executed:

nhibernate-core/src/NHibernate/Loader/Custom/CustomLoader.cs

Lines 348 to 350 in a05f6a9

	if (forcedResultTransformer is CacheableResultTransformer cacheableResultTransformer)
	cacheableResultTransformer.SupplyAutoDiscoveredParameters(
	queryParameters.ResultTransformer, transformerAliases);

But when query is retrieved from cache this part is not executed - thus we have This transformer is not initialized

I think I will provide a fix that skips caching for auto discovery type queries with transformers (so kind of restore behavior before #2943) as I have no better ideas right now

P.S. Another question why it's treated as auto discovery type query? Seems all required types are supplied explicitly...