Microsoft Unity - How to register connectionstring as a parameter to repository constructor when it can vary by client? - c#-4.0

Question

I am relatively new to IoC containers so I apologize in advance for my ignorance.
My application is a asp.net 4.0 MVC app that uses the Entity Framework with a Repository layer on top of that. It is a multi tenant application so the connection string that is used varies by the logged in client.
The connection string is determined by a 'key' that gets passed in as part of the route which indicates the client. This route data is only present on the first request of the user's session.
The route looks kind of like this: http://{host}/login/dev/
where 'dev' indicates we are using the dev database.
Currently the IoC container is registering all dependencies in the global.asax Application_Start event handler and I have the 'key' hardcoded as follows:
var cnString = CommonServices.GetDBConnection("dev");
container.RegisterType<IRequestMgmtRecipientRepository, RequestMgmtRecipientRepository>(
new InjectionConstructor(cnString));
Is there a way with Unity to dynamically register the repository based on the logged in client using the route data that is supplied initially?
Note: I am not manually resolving the repositories. They are getting constructed by the container when the controllers get instantiated.
I am stumped.
Thanks!

Answer 1

Quick assumption, you can use the host to identify your tenant.
the following article has a slightly different approach http://www.agileatwork.com/bolt-on-multi-tenancy-in-asp-net-mvc-with-unity-and-nhibernate-part-ii-commingled-data/, its using NH, but it is usable.
based on the above this hacked code may work (not tried/complied the following, not much of a unity user, more of a windsor person :) )
Container.RegisterType<IRequestMgmtRecipientRepository, RequestMgmtRecipientRepository>(new InjectionFactory(c =>
{
//the following you can get via a static class
//HttpContext.Current.Request.Url.Host, if i remember correctly
var context = c.Resolve<HttpContextBase>();
var host = context.Request.Headers["Host"] ?? context.Request.Url.Host;
var connStr = CommonServices.GetDBConnection("dev_" + host); //assumed
return new RequestMgmtRecipientRepository(connStr);
}));
Scenario 2 (i do not think this was the case)
if the client identifies the Tenant (not the host, ie http: //host1), this suggests you would already need access to a database to access the client information? in this case the database which holds client information, will also need to have enough information to identify the tenant.
the issue with senario 2 will arise around anon uses, which tenant is being accessed.
assuming senario 2, then the InjectionFactory should still work.
hope this helps