NHibernate: How to get mapped values?

Question

Suppose I have a class Customer that is mapped to the database and everything is a-ok.

Now suppose that I want to retrieve - in my application - the column name that NH knows Customer.FirstName maps to.

How would I do this?

Answer 1

I'm not aware that that's doable.

I believe your best bet would be to use .xml files to do the mapping, package them together with the application and read the contents at runtime. I am not aware of an API which allows you to query hibernate annotations (pardon the Java lingo) at runtime, and that's what you would need.

Update: Judging by Jamie's solution, NHibernate and Hibernate have different APIs, because the Hibernate org.hibernate.Hibernate class provides no way to access a "configuration" property.

Answer 2

You can access the database field name through NHibernate.Cfg.Configuration:

// cfg is NHibernate.Cfg.Configuration
// You will have to provide the complete namespace for Customer
var persistentClass = cfg.GetClassMapping(typeof(Customer));
var property = persistentClass.GetProperty("FirstName");
var columnIterator = property.ColumnIterator;

The ColumnIterator property returns IEnumerable<NHibernate.Mapping.ISelectable>. In almost all cases properties are mapped to a single column so the column name can be found using property.ColumnInterator.ElementAt(0).Text.