Global variable for a database connection in Rails

Question

I'm running Rails 3, and I've got several controllers that all do something like the following:

@db = Mongo::Connection.new.db(MONGOID_CONFIG['database'])

I don't want to have multiple connections to the database, so the natural thing would seem to be to wrap @db in some singleton that's initialized when I start the app. My question is, how to do that?

My first thought was to use a helper, but I'm told that those are only recommended for generating view stuff, and obviously views shouldn't be directly accessing the database. What else is there? Write a plugin? :)

Answer 1

first of all, you can write an helper to put, for example, in application_controller.rb, so there's no problem about views (well, view helper normally goes in app/helpers/).

otherwise, you can write the following command and put it in config/initializers/mongo_db.rb:

$db = Mongo::Connection.new.db(MONGOID_CONFIG['database'])

the file will be loaded at boot, $db represents a global variable, so it's avaiable to the entire application (Views included, though), by the way you'll use it only in the appropriate places, right? ;-P

Answer 2

If you're using Mongoid (I assume you might because of your constant being named MONGOID_CONFIG), you can use @db = Mongoid.master.connection to get the Mongo::Connection that's connected to the master db server.