Implementing criteria for unsupported methods

Question

I've written an application that uses LINQ to NHibernate for it's database queries. Code in my domain layer creates expressions of type

System.Linq.Expressions.Expression<Func<T, bool>>

These are passed to repositories in my data access layer, which then use them like this:

return session.Query<T>.Where(expression)...

This was all great before I discovered that NHibernate LINQ provider completely ignores the option fetch="join" in mapping files, meaning that objects are fetched using several select statements rather than a single select with joins.

So I'm trying to move over to the QueryOver API, which fully supports joins. I immediately ran into the problem that methods like string.Equals are not supported. I also have several custom extension methods which I use in my expressions, for which I have added support for in LINQ to NHibernate by extending BaseHqlGeneratorForMethod.

How can I add support for these methods in the QueryOver API? I can't find any information on this.

I'm aware you can do things like this:

Session.QueryOver<T>().WhereRestrictionOn(x=>x.Foo).IsInsensitiveLike("bar")

but I'm looking for a way to do everything using the same expressions that I was using before with LINQ to NHibernate.

Answer 1

The answer seems to be that it's not possible to use lambda expressions with the QueryOver API. As Oskar pointed out in a comment to the question, only very simple lambda expressions are supported. I'm rewriting my code so that the repository methods receive query objects rather than lambda expressions.