[dhh]

Coulda, woulda, damn shoulda. You're future coding with your "what ifs". Most controller actions are not reused. The time to extract for reuse is when you need to reuse. Not crystal balling about that you probably will be in the future.

Because when the reuse case actually arrives, you might find that you need to reuse some, but not all of the action. If you're literally doing the exact same thing for both web and api, why are you using a separate API controller? Just use respond_to with formats.

Second, yes, you shouldn't have side-effects like sending email in your models. But you don't need to! Just stick that logic in your controllers. That's what it's there for -- to render the views (of which emails is one of them -- see http://david.heinemeierhansson.com/2012/emails-are-views.htm...).

The AR callbacks are wonderful for coordinating the domain model. Often times you'll want to create auxiliary objects when something else is created. That's what's it's there for. Or to otherwise keep the integrity of the domain model in place.

[tomblomfield]

Sure, I think we're saying the same thing here.

This example is from a real-life codebase, and the interactor was extracted from 3 or 4 (bloated, repetitive) controllers. Perhaps this could have been made clearer in the post.

I'm not arguing at all that every controller needs an Interactor, or all Rails codebases should start out with Interactors present.

I am saying that Interactors are very useful concepts for re-using code, and that many medium and large Rails codebases could benefit from them.

[dhh]

Please do share the 3 or 4 controllers all sharing this logic. I'd be happy to play code pong with them.

[dablweb]

Regardless of reuse, controller actions can get awfully large if unchecked. What would you say is the maximum LOCs for a public controller method?

Callbacks in Controllers and AR::Models tend to make things worse IMO for anything other than authentication; and for intricate actions interactors seem like the best defence.

I have had the (mis)fortune to jump into a number of large Rails codebases and I can say with hand-on-heart that the only ones that made any sense off-the-bat were ones using a this-or-similar pattern.

The community is embracing policies, interactors and decorators for a reason. Real developers are having real problems when Rails apps get a certain size, and there is no endorsed method on how to handle these problems.

Surely a couple of asides on the Rails docs and some official endorsement could help point new developers in the direction of a possible solution? A solution the industry already seems to be taking; regardless of whether 37Signals deems it fit for their particular domain.

[halostatue]

> What would you say is the maximum LOCs for a public controller method?

As small as it needs to be in order to get the job done, and as large as it must be to get it done clearly. Sometimes that's zero lines of code; sometimes it's 500. You can usually factor down a 500 line method, but it may be worth asking what the breadth cost is should the code really be single-use.

If your metric is anything else, then you're playing Stupid Metrics Games, like that espoused by Code Climate.

[karmajunkie]

"The AR callbacks are wonderful for coordinating the domain model. Often times you'll want to create auxiliary objects when something else is created. That's what's it's there for. Or to otherwise keep the integrity of the domain model in place."

No, they're not. They're great for coordinating activities around your database. That's not a domain model, unless your domain is databases. Conflating domain with database through the use of active record doesn't mean that structural models are domain driven, and events based around database interactions aren't going to be any more domain driven than the active record objects themselves.

[tinco]

Please take a second to think about who you're saying "No, they're not." to. You'd think perhaps that he knows what he has AR callbacks in AR for, regardless of what you might think they're in there for.

The whole idea of ActiveRecord is that you to make your models with a clean interface to persistence. Among the features of that interface are the callbacks. They are there for your domain model to make use of, that's the whole story. If persistence is not part of your domain, why are you extending ActiveRecord?