Question

In my Store model I have the following:

class Store < ActiveRecord::Base
  has_many :categorizations
  has_many :categories, :through => :categorizations

  scope :by_categories, lambda{|category_ids|
    where(*stores have the following* => category_ids) unless category_ids.empty?
  }

I’m looking to setup a scope where I can send it multiple or a single category ID and have the scope return stores that belong to all the categories specified.

Thank you for looking.

Answer 1

class Store < ActiveRecord::Base
  has_many :categorizations
  has_many :categories, :through => :categorizations

  scope :by_categories, lambda { |category_ids|
    joins(:categorizations).where('categorizations.category_id' => category_ids) unless category_ids.empty?
  }
end

>> Store.by_categories([1,2])
=> SELECT "stores".* FROM "stores" INNER JOIN "categorizations" ON "categorizations"."store_id" = "stores"."id" WHERE "categorizations"."category_id" IN (1, 2)