Rails Data Migrations Made Easy!

Introducing ActiveDataMigrations!

From the README file:

ActiveDataMigrations is a Ruby gem that allows developers to set up multiple migration locations, each of which can be run independent of one another. This library sits on top of ActiveRecord so all standard migration features remain available.

This is particularly useful in cases where you want to separate your data migrations from your schema migrations or where you have multiple steps in your migration process that must have other steps invoked throughout.

I’ve always felt that Rails migrations came up short in the area of data seeding and data migration. While you can use the standard schema migrations to manage your data it is a recipe for disaster.

For example, I’ve got my Tanglewood Turnings site that is now in production. I’ve got live customer and order data in the system so I can no longer simply apply a seed or global data update when I push updates out to production. Yet I still have a need to enter large amounts of new data.

In researching the problem on the interweb, the common answer in the Rails community seems to be to either add the data to your migrations files or to create a sql file and apply the changes directly. I personally make it a practice to avoid direct interaction with the database so I explored the migrations route. The problem was that my tests were failing due to the extra and unexpected data. So I added ” unless Rails.env == ‘test’ ” to the end of the data blocks. That stinks. As in bad code smell. Not a good option. The other alternative was to update my tests to accommodate the new data. That would have me updating test cases every time I updated production data. That also stinks.

So I decided to write a solution. I started out with this grandiose idea of somehow abducting the ActiveRecord::Migrator class, while still having it work within the Rails context, and twisting it to meet my own needs. Oh yeah, I also wanted to figure out how to do this without monkey patching. Figuring out how exactly to do this seemingly mundane task took me relatively deep into the Rails and ActiveRecord rabbit hole. While down there I realized that I was vastly over-complicating things and that I could achieve what I wanted with a couple lines of code and a new Rake task. The result was a Ruby Gem that is easy to use, easy to integrate, easy to maintain, and delegates 99.999% of its functionality right back to ActiveRecord, leaving it with the power and reducing my support overhead.

You can install it using:

gem install active_data_migrations

You can read the full write up, view the source, and get more information by visiting the git repository, here:


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Jason McDonald

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