Extracting Rails Model into a GEM

I presently am refactoring an a Rails App that has not only the
standard RoR web front end, but also agents which share the same model
and run on different machines. In the past the whole rails app was
just deployed on other machines even though only the model was used. I
am trying to improve the situation by extracting the model into a gem
which depends only on ActiveRecord and then requiring the model gem in
both my rails application and the agent.

I am finding that my new model gem has a very similar structure to the
rails app with some of the same pieces as the rails app, e.g. boot.rb,
environment.rb, test_helper.rb, etc, albeit scaled down to just the
ActiveRecord specific material. Perhaps this would be a good candidate
for a generator eventually.

One interesting by-product of this approach is that I expect my
fixture data to be easier to maintain since instead of having fixtures
for the unit tests, functional tests for the web, and tests for the
agent all in the same files, these will naturally be broken down into
three separate projects.

In any case I am wondering if anyone else has travelled this road
before and has any experiences they’d like to relate. Did it work
pretty well over the long haul or should I turn back now?

John-Mason Shackelford

Software Developer
Pearson Educational Measurement

2510 North Dodge St.
Iowa City, IA 52245
ph. 319-354-9200x6214
[email protected]

I don’t know about gems, but I’d recommend you look into using plugins.
just wrote a pretty complicated plugin that contains a model. When the
plugin is installed, the model is available to the rest of the
In my case, the model in the plugin actually uses its own database
connection information (because it connects to a central SQL Server

I think a plugin would be useful for your case too. The book “Rails
has some information on using plugins and svn:externals to share models
among applications.

Let me know if I can be any help.