按其方法对Rails模型进行排序

Question

I have a question model, which has_many votes and comments .

I defined a method on the question model called engagement_score which is simply votes + comments .

class Question < ActiveRecord::base
  has_many votes
  has_many comments

  def engagement_score
    self.votes.count + self.comments.count
  end
end

How can I get all questions , sorted by engagement_score ?

Question.all.order("engagement_score ASC") does not work since engagement_score is not a column in questions .

Answer 1

If you don't mind not getting back an array, then you could probably just use sort_by.

So something like

Question.all.sort_by { |question| question.engagement_score } 

Answer 2

You can do something like

Question.includes(:comments, :votes).order_by_engagement_score

def self.order_by_engagement_score
  sort_by |ques|
   -(ques.votes.length + ques.comments.length)
  end
end