NHibernateHelper - many tables - nhibernate

Question

I am new in NHibernate, I have based on tutorial: http://nhibernate.info/doc/tutorials/first-nh-app/your-first-nhibernate-based-application.html . So I have NHibernateHelper:
public class NHibernateHelper {
private static ISessionFactory _sessionFactory;
private static ISessionFactory SessionFactory
{
get
{
if (_sessionFactory == null)
{
var configuration = new Configuration();
configuration.Configure();
configuration.AddAssembly(typeof (Product).Assembly);
_sessionFactory = configuration.BuildSessionFactory();
}
return _sessionFactory;
}
}
public static ISession OpenSession()
{
return SessionFactory.OpenSession();
} }
But I have also entity Category and User? Do I need each entity add to configuration using code AddAssembly?? Because when I have added code:
configuration.AddAssembly(typeof (Product).Assembly);
configuration.AddAssembly(typeof(Category).Assembly);
I have error:
Could not compile the mapping document: MvcApplication1.Mappings.Product.hbm.xml

Answer 1

First check whether you have set the "Build Action" of all the mapping files (*.hbm.xml) to "Embedded Resource". This is VERY important.
Then you only need to add a call to AddAssembly once as NHibernate is clever enough to scan through the assembly to sniff out all your entities that map to all your embedded hbm.xml files..
e.g. You only need to supply the assembly once that contains all your entities:-
_configuration.AddAssembly(typeof (Product).Assembly);
NHibernate will now find Category (and all others) automatically as long as they are in the same assembly as Product. HTH

Answer 2

you can alternatively add the mapping tag into the web.config, instead of adding it in code on the SessionFactory initialization. Then, your code will look like this:
if (_sessionFactory == null)
{
var configuration = new Configuration();
configuration.Configure();
_sessionFactory = configuration.BuildSessionFactory();
}
And in the web config you will have to indicate the assembly where all of your mappings are, like this:
<hibernate-configuration xmlns="urn:nhibernate-configuration-2.2">
<session-factory>
<property name="connection.provider">
NHibernate.Connection.DriverConnectionProvider
</property>
<property name="dialect">
NHibernate.Dialect.MsSql2005Dialect
</property>
<property name="connection.driver_class">
NHibernate.Driver.SqlClientDriver
</property>
<property name="connection.connection_string">
-- YOUR STRING CONNECTION --
</property>
<property name="proxyfactory.factory_class">
NHibernate.ByteCode.Castle.ProxyFactoryFactory, NHibernate.ByteCode.Castle
</property>
<mapping assembly="You.Assembly.Namespace" />
</session-factory>
Being the important configuration tag "mapping assembly="Your.Assembly.Namespace". As the other contributor mentioned before, it is very important that you mark each of the hbm.xml file as embedded resource, otherwise it will be as you never created it. By doing this, you just need to create all of the mappings inside of this assembly (project) and those will be automatically read when NH configures.