Chapter 9. Incorporating and Extending Rails

The best way to predict the future is to invent it.

—Alan Kay

Ruby on Rails was designed as a loosely coupled set of components (ActionPack, ActiveRecord, ActiveResource, ActiveSupport, and ActionMailer) with some glue to hold them together (RailTies). Although Rails is typically used as a framework (an environment specialized to programming web applications), the components of Rails can be replaced with other components more suitable to a project. Alternatively, the components can be broken out and used apart from the rest of Rails. In this chapter, we will see how these techniques can be used for maximum flexibility in application development.

Replacing Rails Components

Replacing ActiveRecord

ActiveRecord, the Rails object-relational mapper, is one of the best-known parts of the Rails framework. But it represents one of many valid ways to map objects to a database. Martin Fowler identified and defined the Active Record pattern, along with other data-source patterns, in his book Patterns of Enterprise Application Architecture. (The Active Record pattern should not be confused with the ActiveRecord library, which is based on that pattern.) Several Ruby libraries have been developed based on other patterns. We will look at DataMapper, based on the pattern of the same name. We will also examine Ambition, an off-the-wall experimental library that maps Ruby statements directly to SQL.

If you are not using ActiveRecord in a Rails application, ...

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