I downloaded NHibernate 2.0 today and started to play around with it, only to be greeted by a host of configuration errors like System.InvalidOperationException : Could not find the dialect in the configuration. It was then I remembered reading somewhere about some changes to the configuration syntax, so I downloaded the source and looked at the examples (after a brief, ill-fated search for NHibernate 2.0-specific documentation*).

Here is an example of how an App.config looked for NHibernate 1.2:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="nhibernate" type="System.Configuration.NameValueSectionHandler, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
  </configSections>
  <nhibernate>
    <add key="hibernate.connection.provider" value="NHibernate.Connection.DriverConnectionProvider" />
    <add key="hibernate.dialect" value="NHibernate.Dialect.MsSql2005Dialect" />
    <add key="hibernate.connection.driver_class" value="NHibernate.Driver.SqlClientDriver" />
    <add key="hibernate.connection.connection_string" value="Data Source=127.0.0.1\SQLEXPRESS;Initial Catalog=DbWorkshop;Integrated Security=True" />
  </nhibernate>
</configuration>

And here is the equivalent for version 2.0:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="hibernate-configuration" type="NHibernate.Cfg.ConfigurationSectionHandler, NHibernate" />
  </configSections>
  <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">Data Source=127.0.0.1\SQLEXPRESS;Initial Catalog=DbWorkshop;Integrated Security=True</property>
    </session-factory>
  </hibernate-configuration>
</configuration>

The main changes are:

• We aren’t using an nhibernate configuration section, it’s hibernate-configuration now (yay for more typing! :P).
• We now have a session-factory child node for adding the configuration properties.
• We aren’t adding properties using the <add key="..." value="..." /> syntax. Instead we are using <property name="...">(property value)</property>.
• The property names aren’t prefixed by "hibernate" anymore, so "hibernate.connection.provider" becomes "connection.provider".

Moral of the story is to check the source first – the NHibernate.Examples folder is filled with helpful goodies. :) Svend Tofte also has a helpful post on setting up NHibernate 2.0.