Atmospheric Labs

By now, we all know that named_scope is one of the most useful Rails features ever. It’s the kind of thing that makes me wonder how I ever lived without it. I’m currently refactoring some old code and finding that using named_scope can make for some really long chains sometimes. They almost seem…too long.

For instance, I have an Update model which contains both news items (short blurbs) and articles (longer updates). Some articles are also for internal eyes only (via admin pages). When someone is viewing a news item, the 5 latest updates appear in the sidebar, but I can’t be listing the one they’re currently viewing!

In the tradition of small view / huge model, I’ve attempted to move all the logic into the model.

Model / update.rb

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  named_scope :public, :conditions => "internal_only = 0", :order => 'updated_at desc'
  named_scope :news, :conditions => "update_type = 'news'"
  named_scope :articles, :conditions => "update_type = 'article'"
  named_scope :limit_to, lambda { |l| { :limit => l } }
  named_scope :except, lambda { |i| { :conditions => [ "id != ?", i ] } }

In a view or helper method (object = currently displayed item)

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  news = Update.public.news.limit_to(5).except(object.id)
  articles = Update.public.articles.limit_to(5).except(object.id)

Now, this works great, but that’s getting to be a mighty long scoping chain. So, the burning question - can this chain ever get too long?

Rails, Ruby