Using dynamic connection strings

There are cases where an application may need to change connection strings depending on some condition. This can be in the context of a multi-tenant application, or perhaps a database failover scenario. In this recipe, we'll show you how to switch NHibernate connection strings at runtime.

How to do it…

1. Start a new console application project named DynamicConnectionString.
2. Add references to NHibernate.dll, log4net.dll, and the Eg.Core model from Chapter 1, The Configuration and Schema.
3. Add a reference to System.Configuration from the .NET framework.
4. Set up App.config with a standard NHibernate and log4net configuration.
5. Add the following DynamicConnectionProvider class:

   public class DynamicConnectionProvider : 
     DriverConnectionProvider
   {
   
     private const string ANON_CONN_NAME = "db";
     private const string AUTH_CONN_NAME = "auth_db";
   
     protected override string ConnectionString
     {
       get
       {
         var connstrs = ConfigurationManager...