At the Forge - Working with ActiveRecord

Reuven Lerner continues his series on Ruby on Rails with this look at database integrity checking using ActiveRecord.

Although constraints in our database ensure that the data will always be valid, we generally want to perform such validation at the application level. Unfortunately, doing so is tricky or time consuming in many languages. ActiveRecord, the object-relational mapper at the heart of Ruby on Rails, makes it relatively easy to ensure that your users never have to see a database error. It comes with a number of validators, as well as an infrastructure for creating custom ones. Moreover, it comes with a number of routines that let us describe the relationships among different tables. With some small modifications to the controllers, views and models, we are able to create a custom application with valid data quickly.

Resources for this article: /article/8580.

Reuven M. Lerner, a longtime Web/database consultant and developer, now is a graduate student in the Learning Sciences program at Northwestern University. His Weblog is at, and you can reach him at



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