rails/activerecord search eager loaded associations

Question

I have a simple find statement as such:

m = MyModel.find(1, :include => :my_children)

With m.mychildren being an Array; is there anyway to find a particular record from within the array without having to iterate over the entire thing. If I do mychildren.find(1), a new DB query is issues, which doesn't make sense, since they are all loaded already

Answer 1

I'm not quite sure what your asking, but have you tried select:

m.mychildren.select{ |child| child == <<some_statement>> }

This won't hit the database assuming you've used the :include option as you stated in your question.

Alternatively, if you know the number of the child you want, you should be able to just use

m.mychildren[1]

Answer 2

It looks like there's a little Rails magic going on here. Where Enumerable#find is being overridden by ActiveRecord::Base#find on methods created for associations.

On the upside Enumerable#find is aliased to Enumerable#detect. Unfortunately Enumerable#find/Enumerable#detect have significantly different syntax from ActiveRecord::Base#find.

So you can't just do mychildren.find(1), instead you've got to do mychildren.detect{|c| c.id == 1} if you want to avoid hitting the database again. You may also want to consider extending Array for a more DRY way of doing this.

class Array 
  def id_find id
    self.detect{|element| element.id == id}
  end
end