R – Handling Multiple databases with NHibernate in a single application

multiple-databasesnhibernatesession

At the moment I define the connection properties in a configuration file and only ever connect to one database. I'd like to be able to at some point have a user login, figure out (via a seperate central database maybe) what database they should be connected and from that point on all sessions created will talk to that database.

Whats the best way to achieve this. Create a configuration file for every possible database? Or could I have a single session manager and change the connection url on the fly accordingly? What sort of options do i have?

Update: Apologies I should have mentioned this was NHibernate. I didn't think it would matter but some things like Hibernate Shards will not be applicable to be as I believe NHibernate Shards is waiting.

Best Answer

You just need to make two datasources then call the one you need for the specific query.

Please take a look at this:

https://www.hibernate.org/450.html

Some official solutions.

And here:

http://www.java-forums.org/database/159-hibernate-multiple-database.html

an online thread about this issue.

Related Solutions

R – NHibernate using single configuration file to connect to multiple dbs

Use the ISessionFactory.OpenSession() overload that takes a IDbConnection.

That's how Castle's DifferentDatabaseScope does it.

R – Opening multiple sessions simultaneously in NHibernate

I figured out how to fix the problem. I setup my SessionFactory as a singleton at made it [ThreadStatic] like this:

[ThreadStatic]
private ISessionFactory _sessionFactory;

[ThreadStatic]
private bool _isInitialized;

public ISessionFactory SessionFactory
{
    get
    {
        if(!_isInitialized)
        {
            //Initialize the session factory here
        }
    }
}

The crux of the problem is that creating sessions on separate threads from the same ISessionFactory is problematic. ISessionFactory does not like multiple ISessions being opened at the same time. Closing one, automatically closes any others that are open. Using the [ThreadStatic] attribute creates a separate ISessionFactory for each thread. This allows me to open and close ISessions on each thread without affecting the others.

Best Answer

Related Solutions

R – NHibernate using single configuration file to connect to multiple dbs

R – Opening multiple sessions simultaneously in NHibernate

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