I'm building my own "HQL Query Analyzer" and an HqlObjectDataSource class and corresponding designer for use in Visual Studio. So, given an arbitrary HQL query string, I would like to determine the names and types of the query parameters. E.g. if my query string is



I would like to call some NHibernate method that returns an instance of NHibernate.Engine.QueryParameters that defines "foo" and "bar". In the returned QueryParameters.NamedParameters, the Value in each NHibernate.Engine.TypedValue would be a uninitialized (or otherwise meaningless), but that's fine, all I care about is getting the Name and Type properties for each parameter.

Internally, NHibernate needs to determine this parameter information when it executes queries. The question is, does NHibernate properly break out this parsing task to an API method I can call? And if so, what is that call? I'm looking in the NHibernate.Hql namespace, and see a QueryTranslator object which takes a query string. I also see various Parser classes in this namespace. However, nothing jumps out at me as the method or property to call to get this query parameter information for a given query string ...

You could try getting at the SqlString object that is generated by the QueryTranslator. An SqlString is a list of parts, each part either of type String or Parameter, with Parameter objects having name and type.

The type of Parameters is a database type though (SqlType, not IType).

No, that wouldn't do it, I need the HQL parameters, not the SQL parameters. I can hack together a parsing method to pull out the named parameters from an HQL query string, that's no big deal -- the real problem is how to determine the "required" NHibernate.Type.IType for each parameter. Doesn't NHibernate do that somewhere when it executes HQL queries with named parameters -- i.e. how does it determine if a parameter value can or cannot be assigned?

No, it actually doesn't determine the type anywhere - you are required to supply the type along with the parameter value and NHibernate relies on that supplied type.