Fri, 29 Sep 2006

Rails Across 3 Oracle Databases

Short version: Rails can integrate wonderfully across multiple legacy Oracle databases.

Longer version:

Over the course of my Rails development experience, I've (wrongly) assumed that trying to get Rails to do enterprise'y things is difficult. I'm not going to go into why I assumed this, but I would bet that there are others out there who have been scared into believing that they shouldn't try to swim against the Rails' convention of a single database with specific table-naming conventions.

My assumption was blown out of the water this morning when my pair and I needed to grab data from 2 other databases for a little Rails app that we created yesterday. The app was the brain-child of our client manager who needed a way to track the status of features and bug-fixes as they progressed through QA. We use XPlanner for iteration planning and iTracker for bug tracking, so she wanted to be able to refer to an XPlanner story id and/or an iTracker issue id for each QA task. We were able to deliver this to production in about an hour (thank you Capistrano) yesterday afternoon (yes, T is approaching zero).

This morning, our client said that she didn't want to see the issue and story ids, she wanted to see the name of the issue and story. For that, we needed to grab them from the XPlanner and iTracker databases. With much wringing of hands, and prepared to see our Rails productivity plummet, we Google'd around to see how to connect to multiple databases in Rails. First, we needed to configure our databases:

config/database.yml
production:
  adapter: oci
  username: foo
  password: 
  host: FOO:5353/BAR

planner:
  adapter: oci
  username: xplanner
  password: 
  host: (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=...

tracker:
  adapter: oci
  username: itracker
  password: 
  host: (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=...

app/models/story.rb
class Story < ActiveRecord::Base
end

app/models/issue.rb
class Issue < ActiveRecord::Base
end

app/models/task.rb
class Task < ActiveRecord::Base
  belongs_to :issue
  belongs_to :story
  ...
end

config/environment.rb
Story.establish_connection "planner"
Story.set_table_name "story"

Issue.establish_connection "tracker"
Issue.set_table_name "issuebean"

task = Task.find(1) # from prod Oracle database
puts task.story.name # from XPlanner Oracle database
puts task.issue.description # from iTracker Oracle database

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