Introduction

Connection Ninja is a really simple gem to help connection to multiple databases. I wrote it to help with the way we were connected a new application at work to our older application that holds the data we needed to do reporting on. We have code (models) that is shared between those two applications, and I wanted them to be able to connect to the correct database regardless which app they were in, and therefore which database.yml they were reading.

Installation

Due to hopefully everyone upgrading to rails 3, if you need to use this with Rails 2.x just install the old version.

Install the gem:

Rails 2.x

gem install connection_ninja -v 0.3.5

Rails 3

gem install connection_ninja

Configuration

class MyModel < ActiveRecord::Base
  use_connection_ninja(:database)
end

After your normal configuration in database.yml add a new group:

database:
  development:
    adapter: postgresql
    database: database_name
    user: username

  test:
    adapter: postgresql
    database: database_name
    user: username

  production:
    adapter: postgresql
    database: database_name
    user: username

WHY?

Pure laziness. Rather than putting together a hash you can just call a group with use_connection_ninja(:group)

How I used it

To get my 20 or 30 models to all use one connection I used a simple abstract class to do it. I also got to learn about these along the way

class OtherConnection < ActiveRecord::Base
  self.abstract_class = true
  use_connection_ninja(:database)
end

So I could:

class ModelFromOtherDB < OtherConnection

end