Rails: any way to refactor this ActiveRecord code?

Question

I have a piece of code that checks that a survey response picked by user to a survey question is in fact one of valid choices:

Question.find_by_id(question_id).question_choices.all(:select => 'id').map {|x| x.id}.include?(user_choice_id)

Is there an easier way? Thanks!

Answer 1

At the very least the question_choices.all(:select => 'id').map {|x| x.id} component can be rewritten, as ActiveRecord provides a method for this question_choice_ids.

You can also just do find instead of find_by_id. I know that find will raise an exception if nothing is found, but so will calling question_choices on nil in your example, anyway:

Question.find(question_id).question_choice_ids.include?(user_choice_id)

# or 

# Rails 2 (will run 2 queries unless you use :include)
Question.find(question_id).question_choices.first(:conditions => {:id => user_choice_id})

# Rails 3 (will only run 1 query)
Question.find(question_id).question_choices.where(:id => user_choice_id).first