CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-3postgresql
WhoDidThis
WhoDidThis

Reputation: 383

Rails 3: Filtering results by counting children

I'm working on an approval system where an example would be filtered out if it had more negative approvals than positive.

class Set < ActiveRecord::Base
  has_many :examples
end

class Example < ActiveRecord::Base
  has_many :approvals, as: :approvable
end

class Approval < ActiveRecord::Base
  belongs_to :approvable, polymorphic: true
  belongs_to :example
  attr_accessible :choice #boolean
end

I can get all approvals belonging to an Example by calling Example.approvals.

What i'm wondering about is if it's possible to create a method on Example model that i could then use a la Example.approved that would return true or false with a single query depending on if the example has more Approvals with true or false. Ultimately i would want to call only the examples of a set that have been approved by calling Set.approved_examples.

Example.approved i can kind of do with

class Example < ActiveRecord::Base
  ...
  def approved
    if approvals.where(choice: true).count > approvals.where(choice: false).count
      return true
    end
    false
  end
end

although that takes two queries.

Set.approved_examples would look like the SQL View approved_examples in here but i'm not sure where to start if i wanted a scope like this on the Set model.

Upvotes: 0

Views: 286

Answers (1)

sq1020
sq1020

Reputation: 1090

Okay, based on your comment I think I misunderstood your question but maybe you coudld try something like this:

Example.all.select { |example| example.approved == true }

That would get you an array of all approved examples.

Set.first.examples.all.select { |example| example.approved == true }

That would get you an array of all approved examples that belong to the first set record.

I think there's probably a more optimal way to do this, but this does work.

Upvotes: 1

Related Questions