I've been looking at Rails lately, partly to see what the hype is about and partly to see what useful elements can carry over into my ColdFusion development. One of the things that I have pretty deep concerns over is its focus on the Active Record pattern. Most books and tutorials go so far as to recommend building your database first and then working backwards from that!

It would be interesting to have a discussion on whether it is a bad idea (and I think it is) to work backwards from a relational database model and hammer this down on top of your domain model. But I don't want to go there just yet. What I wanted to talk about is the Active Record design pattern itself.

Active Record (or ActiveRecord if you prefer) underpins almost everything you will see about Rails. It is the reason why "the database comes first" for most Rails folks. And I won't argue that it seems to have some nice advantages. It handles relationships and SQL and all that boring database stuff. It makes things like scaffolding not only possible, but fairly simple. Because a lot of web applications ARE actually just CRUD front ends for database data, Active Record might often be just the ticket.

However, Active Record is supposed to be a design pattern. So why it that if I Google for "'Active Record Pattern' Consequences", I get only 33 results? 33! Where a search for "Active Record Pattern" alone brings back ten thousand?

Design Patterns are supposed to be defined in a very specific way. One of the parts of that definition is to describe the consequences. These are the drawbacks or implications of using that pattern. I'm not sure why, but for some reason no one seems to be considering the consequences of the Active Record pattern. In fact, even of the 33 results I could find, none of them actually discuss the consequences of the pattern. They just happen to be results where the word "consequences" happened to be somewhere on the page. I could not find a single pattern definition for Active Record that actually discussed the consequences (or most of the other established elements that should be present when defining a pattern).

First, does someone know if I am missing something? Is there some reason why no one would be considering the consequences of this hugely popular pattern? The cynic in me almost wants to think that someone (I believe it was Fowler, who I admire greatly) came up with this idea, and then a lot of other people just grabbed it and ran with it, slavishly applying it without really giving it any more thought. Does anyone have any ideas on this? Why is Active Record, as far as I can tell, such a popular "pattern" that actually doesn't seem to have a real pattern definition?