Question

I want to select the Resources that are used by the most users.

The Models:

class Resource < ActiveRecord::Base
  has_many :users, :through => :kits
  has_many :kits

class User < ActiveRecord::Base
  has_many :resources, :through => :kits
  has_many :kits, :dependent => :destroy

class Kit < ActiveRecord::Base

  belongs_to :resource
  belongs_to :user

I want to create a scope that selects those resources whose resource.users.count > 3

How can I do this in Rails?

Thanks

I am getting close but still have some issues:

scope :most, group('resources.id, resources.title, resources.url, resources.description, resources.author, resources.price, resources.created_at, resources.updated_at').joins(:users).having("count(user_id) > ?",5)

I have had to include all the fields for a resource because Postgresql is giving an error as follows:

ActiveRecord::StatementInvalid: PG::Error: ERROR:  column "resources.category_id" must appear in the GROUP BY clause or be used in an aggregate function

There must be a way to include all the fields without having to type out each one

Answer 1

This should work:

class Resource < ActiveRecord::Base
  def popular_resources
    joins(:users).where("users.count > '3'")
  end