I’ve long suspected that David Heinemeier Hansson is some kind of mindreader. This morning, when Rails 0.12 came out, I’m even more convinced about that.

Eager loading of associations.

This is a very cool addition to the arsenal of ActiveRecord. You can now select which associated objects get loaded automatically when you use find to get a bunch of things from the database.

Example:

for model in Model.find(:all, 
                  :include => :products) do
  puts "Title:            " + 
     model.title
  puts "Number of models: " + 
     model.comments.size
end

In the olden days, this kind of code would have meant N+1 sql queries where N is the number of models. And now? One. Uno. Ett. The magical include clause in the find call causes Rails to automatically craft a join query that fetches not only the model objects but also all the product objects associated to them.

Even better AJAX support

This is what got me thinking about DHH’s supernaturality. Last week I was playing around with the new AJAX stuff and noticed that there was no way to specify the “normal” href attribute in the AJAX-powered links and forms, for those people who don’t have a browser supporting ajax (mainly people with disabilities). Well, I didn’t even have time to write a ticket about it when it’s already fixed.

Not convinced yet? Ok. How about this. I’m writing a simple intranet for our club and thought that it would be cool to have a simple bulletin board on the front page where people could just leave quick, non-threaded messages with AJAX. The problem was that even when the writer can see her note in no time, others can’t. So periodically_call_remote to help, updating the given part of the page periodically.

OK, but stop listening to me. Go read the full post about the enhancements yourself.