Make query with association and search by custom model method rails - ruby-on-rails

Question

I have this problem, i tried to get all Beauty Salons when the service has a promotion, but service has a custom method and return true or false, this is the structure of my code
class BeautySalon < ActiveRecord::Base
has_many :services
end
class Service < ActiveRecord::Base
belongs_to :beauty_salon
has_many :service_promotions
has_many :promotions, through: :service_promotions
def has_promotion?
## consult another tables and return true or false if found a promotion
end
end
iam tried to make the query like this
BeautySalon.all.includes(:services).select('services.*').select{|service| service.has_promotion?}
but rails return this error
NoMethodError (undefined method `has_promotion?' for #BeautySalon:0x0055a1119d1f40)
Any advice for this?
UPDATE
the method has_promotion do this
def has_promotion?
if promotions.exists?
if get_promotions(Date.today).exists?
return true
else
return false
end
end
return false
end
def get_promotions(date)
if promotions.exists?
promotions.where('start_date <= ? and end_date >= ?',date,date)
end
end
and another tables are there
class Promotion < ActiveRecord::Base
validates :discount, presence: true
validates :start_date, presence: true
validates :end_date, presence: true
has_many :service_promotions
has_many :services, through: :service_promotions
end
class ServicePromotion < ActiveRecord::Base
validates :service_id, presence:true
validates :promotion_id, presence:true
belongs_to :service
belongs_to :promotion
end
thanks for all the advises

Answer 1

BeautySalon.joins(:services).select { |beauty_salon| beauty_salon.services.any?(&:has_promotion?) }
This is an option. You are now calling has_promotion? on the wrong object (e.g. beauty salon instead of service) and the error is raised because the instance method is defined in Service.rb.
It would be better in my opinion to add a database column has_promotion (boolean) to your services table.
BeautySalon.joins(:services).where(has_promotion: true)
If has_promotion? simply retrieves data from another associated model (other_association, with db boolean column promotion) you can also do something like this:
BeautySalon.joins(services: other_association).where(other_association: { promotion: true })
Update:
BeautySalon.joins(services: :promotions).where("promotions.start_date <= :date AND promotions.end_date >= :date", date: Date.current )
This will return all beauty salons with running service promotions (today).