ActiveRecord (and Rails) Considered Harmful

http://blog.steveklabnik.com/posts/2011-12-30-active-record-considered-harmful

by michaelty • 15 years ago

39 18 15 years ago

blog.steveklabnik.com

bdimcheff• 15 years ago

I've had many of the same thoughts about Rails over the years. I think the view model idea is definitely worth exploring... it would certainly rid models of a bunch of view-related stuff that doesn't manage to end up in helpers.

One piece of coupling that really bugs me is doing stuff like link_to(@foo) that will autogenerate a URL based on the class name of the model. To me, this is way worse than the table names and makes the routes highly coupled with the underlying class naming structure. Way too much magic...

gerggerg2• 15 years ago

That's a poster child of convention over configuration. One huge benefit of which is maintainability.

tjogin• 15 years ago

Uh, "magic" code isn't "magic", it's just code you don't understand. The obvious solution is to stop writing it off as "magic" and learn to understand it.

obiefernandez2• 15 years ago

Overly alarmist headline, although there are some good points of discussion in there, especially for Rails newbies. The article left a bad taste because it didn't elaborate on well-known solutions for the problems cited.

For instance, the sole problem mentioned with ActionController is the use of instance variables to communicate state to the view templates. The popular decent_exposure gem [1] eliminates this problem by giving you a declarative way to program to the controller's stated interface. It completely eliminates the need for using instance variables in your controller code.

[1] https://github.com/voxdolo/decent_exposure

jordinl2• 15 years ago

why is it a problem anyway?

obiefernandez2• 15 years ago

Use of instance variables to communicate state to views is known to lead to implicit and tight coupling between controller and templates (and become a nightmare to maintain over time)

DHH disagrees with this point of view because he considers templates to be methods of the Controller optimized for generating text. Hence use of instance variables is not a problem.

phamilton• 15 years ago

I'm glad Obie chimed in. Most of the points discussed in the article (like decent_exposure) are discussed in his book, The Rails 3 Way. Others, like presenters, have had recent RailsCasts about them.

Rails 3.1 seems to provide a "best of both worlds" when it comes to convention over configuration. It feels a lot more modular and configurable, yet still does most of the work for you. I don't feel Rails itself provides much friction, and areas that do are easily overcome with gems from the community.

bretthopper• 15 years ago

The only way to stop putting too much logic in your views is to switch a logic-less templating system. I'm convinced that willpower, coding standards, code reviews, etc would never be enough to stop it.

Here's a decent implementation of mustache for Rails: https://github.com/goodmike/mustache_rails3

app/views becomes .rb files which act as a sort of presenters.

app/templates is where your actual mustache templates go.

There's a lot of benefits to this and a huge one is being able to reuse templates on the client-side.

bradleyland• 15 years ago

> The real issue is that changing these things would require some really serious changes. It'd involve re-architecting large portions of things that people classically identify with Rails, and I'm not sure that Rails wants to or can do that.

Remember Merb? Remember Rails 2.x -> 3.x? These were not small changes, and the community negotiated them successfully.

What I'm saying is, don't get discouraged. The fact that we, as a community, can be openly critical of our tools is the only way to move them forward. Yes, there are a lot of blind followers who will defend anything Rails, but I've noticed that the core contributors are far more open minded about discussing the warts.

This doesn't mean they'll agree with everything you've said though. Theoretically pure scripting languages are under-represented in the general community? Why is that? I think the simplest answer is that they're beyond the grasp of most programmers. Digressing further, it begs the question of "what problem do you want to solve?" That is ultimately what any discussion will revolve around. Where will the balance between purity and accessibility land? Fortunately, I think there's progress being made there.

jordinl2• 15 years ago

"It took me two and a half years to realize that Ruby classes in the models folder don't have to inherit from ActiveRecord::Base. That is a problem."

Wow! Maybe you're the problem...

"ActionController relies on instance variables to pass information from the controller to the view. Have you ever seen a 200 line long controller method? I have."

Well I haven't, I've actually seen it in Django. Nothing forces you to write 200 lines controller methods.

"The whole idea of logic in templates leads to all kinds of problems."

Again, nothing forces to write a lot of logic in the views, you could write the minimum necessary.

karmajunkie• 15 years ago

If you haven't seen those kinds of controller methods, I'm wondering if you've worked on any legacy apps recently? I've yet to see an app with a) more than one or two skilled developers and b) more than a couple of years old that C) didn't exhibit that problem in at least a couple of spots. I don't think this is a Rails problem—its a code discipline problem. If you're fortunate enough to have only worked on solo projects or teams with extraordinary discipline, then I'm jealous! But its definitely a problem that creeps into most codebases sooner or later.

zalew• 15 years ago

"The differences between Django's idea of 'views' and Rails' idea of 'views' are interesting here."

Yep. Actually, Django's MVC implementation is commonly called MTV (afaik it's not an official term) because the 'views' are in fact controllers.

gerggerg2• 15 years ago

It's a bummer this article starts out with a quote about Rails providing a bad OOP learning environment and then talks about the framework itself never touching on the learning of OOP again.

    "it's lead Rails developers to build huge, 
    monolithic models that are hard to test, 
    and violate SRP."

...Sounds like you need to structure your code better.

    "Have you ever seen a 200 line long 
    controller method? I have."

... What on earth are you talking about? This has nothing to do with rails. Structure your code better.

    "The whole idea of logic in templates 
    leads to all kinds of problems."

...Then don't put logic in your templates. Use helpers or logic-less templates.

    "MVC has served the web well... 
    ...But I think we're reaching its 
    limits"

...If the type of web app you want to make isn't best constructed with an mvc framework, don't use mvc. But honestly, I can't think of anyway to more blissfully implement a RESTfull webapp than with respond_to and resourceful routes.

    "This post is light on examples. 
    I want this to be the starting point 
    of a discussion"

...This exact discussion has been raging for years. Your only chance at gaining ground is through examples.

This brings me to: When is this post from? I feel like it's 5 years old and I've slightly been had.

samstokes• 15 years ago

I think his thesis is that Rails should help developers avoid those pitfalls. That's half the point of a framework (as opposed to a library): to show you how to structure your code better.

That's actually a big part of the value of Rails: it picks one of the many ways to structure a web application (MVC with templates and an ORM), provides code to support that way, and (relevantly) sets conventions for code structure, directory layout (app/models/, lib/, etc).

It could have left some of those as plugins - like how Sinatra provides only routing and templating, and if you want MVC or ORM, you have to add them. But by making them part of the framework, Rails declared "here is one good way to structure a web app".

By pushing MVC, Rails helped developers avoid the pitfalls of one-page-PHP apps (mysite.com/index.php?page=news) - big entangled codebases with database access, HTML generation and business logic all intermixed. ActiveRecord helped developers avoid SQL injection attacks, repetitive query generation, and sprawling ORM config files. They made those problems trivial to avoid, and thus advanced the state of web development.

The OP acknowledges those contributions of Rails and ActiveRecord, but argues it's time for them to advance again, as there are new problems they need to tackle.

hardboiled• 15 years ago

Rails is opinionated (and there is some entrenched baggage from the way PHP did things). It actually requires considerable effort to be able to structure your code with OO best principles with decoupled dependencies. Klabnik doesn't go too much in OO principles but Uncle Bob has spoken about this before:

http://confreaks.net/videos/759-rubymidwest2011-keynote-arch...

martinvanaken• 15 years ago

Same here. I think those discussions are useful because, as you, I think Rails is really nice, but it does hurt my domain driven design optic. I think many people are searching various way to overcome the ActiveRecord "problem" (/design decision). I saw a presentation by Corey Haines on this recently, and it did gave me some food for thought : http://blog.8thcolor.com/2011/11/arrrrcamp-fast-rails-tests/.

I'm currently working on a new Rails project, and I'm delegating more and more responsibility to model objects that does -not- extends ActiveRecord. Works for me, for now.

cheald• 15 years ago

If you're interested in "view models", then check out Draper:

https://github.com/jcasimir/draper

It provides exactly that, and it was a huge "a-ha!" for me when I started using it. Suddenly, things that felt icky to do in a helper (because they were tightly coupled to a model) or in the model (because they rightly belonged in a view helper) had a place to live. My templates are nearly fully devoid of twisting logic now.

Based on my experience, I think that Rails is missing the decorator/view-model piece, and would benefit from it as a core addition, but one of the great things about Rails is that it's easily extensible. Drop the gem in your gemfile, start using decorators, and go home happy.

sebastian_e• 15 years ago

From the article:

    "I've written a lot of crappy code, and most of it is due to following Rails 'best practices.'"

Funny how the author purposes to be following 'best practices' yet is doing things such as writing 200-line methods full of if statements, putting logic in views, etc. It seems the authors woes stem directly from a lack of 'best practice' knowledge, not only of Rails but also of Ruby itself.

There will never be a framework that can completely stop developers from shooting themselves in the foot. Education is the key.

(I'll admit this comment could be much more helpful in as much as stating what the best practices are which would solve or prevent these problems but I would be repeating ground covered by better teachers than I. The truth is out there, seek and ye shall find, etc, etc!)

ActiveRecord (and Rails) Considered Harmful

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