Nhibernate mapping at run time - nhibernate

Question

I am developing a site in which nhibernate is using. that is working fine for static mapping. but problem that i apply this application on existing database. so is there any way that mapping of classes took place at run time. i mean user provide tables and column names for mapping. Thanks

Answer 1

From your question I interpret you saying that the POCO classes exists, but you don't know the table or column names at build time.
So, if you already had this class:
public class MyGenericClass
{
public virtual long Id { get; set; }
public virtual string Title { get; set; }
}
You could bind it to a table and columns at runtime:
string tableName; // Set somewhere else by user input
string idColumnName; // Set somewhere else by user input
string titleColumnName; // Set somewhere else by user input
var configuration = new NHibernate.Cfg.Configuration();
configuration.Configure();
var mapper = new NHibernate.Mapping.ByCode.ModelMapper();
mapper.Class<MyGenericClass>(
classMapper =>
{
classMapper.Table(tableName);
classMapper.Id(
myGenericClass => myGenericClass.Id,
idMapper =>
{
idMapper.Column(idColumnName);
idMapper.Generator(Generators.Identity);
}
);
classMapper.Property(c => c.Title,
propertyMapper =>
{
propertyMapper.Column(titleColumnName);
}
);
}
);
ISessionFactory sessionFactory = configuration.BuildSessionFactory();
ISession session = sessionFactory.OpenSession();
////////////////////////////////////////////////////////////////////
// Now we can run an SQL query over this newly specified table
//
List<MyGenericClass> items = session.QueryOver<MyGenericClass>().List();

Answer 2

I don't think that could be possibly with NHibernate, but you could use a workaround.
You could use a view instead a table for the NHibernate mapping.
And in runtime, you could create that View or update it with the especified user mapping you need.
For example, you define a mapping in NHibernate to a view named ViewMapped with two columns Name and Mail.
And in the other hand, the user has a table with three columns Name, SecondName, EMail.
you can create a view on runtime with the following select:
(SELECT Name + ' ' + SecondName as Name, EMail as Mail FROM tableName) AS ViewMapped
I hope that helps you, or at least leads you to a solution.