Question

This seems like a really simple question but I haven’t seen it answered anywhere.

In rails if you have:

class Article < ActiveRecord::Base    has_many :comments  end  class Comments < ActiveRecord::Base    belongs_to :article  end 

Why can’t you order the comments with something like this:

@article.comments(:order=>'created_at DESC') 

Named scope works if you need to reference it a lot and even people do stuff like this:

@article.comments.sort { |x,y| x.created_at <=> y.created_at } 

But something tells me it should be simpler. What am I missing?

Answer 1

You can specify the sort order for the bare collection with an option on has_many itself:

class Article < ActiveRecord::Base    has_many :comments, :order => 'created_at DESC' end  class Comment < ActiveRecord::Base    belongs_to :article  end 

Or, if you want a simple, non-database method of sorting, use sort_by:

article.comments.sort_by &:created_at 

Collecting this with the ActiveRecord-added methods of ordering:

article.comments.find(:all, :order => 'created_at DESC') article.comments.all(:order => 'created_at DESC') 

Your mileage may vary: the performance characteristics of the above solutions will change wildly depending on how you’re fetching data in the first place and which Ruby you’re using to run your app.