How to best handle per-Model database connections with ActiveRecord?

Question

I'd like the canonical way to do this. My Google searches have come up short. I have one ActiveRecord model that should map to a different database than the rest of the application. I would like to store the new configurations in the database.yml file as well.

I understand that establish_connection should be called, but it's not clear where. Here's what I got so far, and it doesn't work:

class Foo < ActiveRecord::Base
    establish_connection(('foo_' + ENV['RAILS_ENV']).intern)
end

Answer 1

Heh. I was right! More cleanly:

class Foo < ActiveRecord::Base
    establish_connection "foo_#{ENV['RAILS_ENV']}"
end

Great post at pragedave.pragprog.com.

Answer 2

Also, it is a good idea to subclass your model that uses different database, such as:

class AnotherDatabase < ActiveRecord::Base
  self.abstract_class = true
  establish_connection "anotherbase_#{RAILS_ENV}"
end

And in your model

class Foo < AnotherBase
end

It is useful when you need to add subsequent models that access the same, another database.