obdev/app/models/employer.rb

class Employer < ApplicationRecord
  # Direct association with participants
  has_many :direct_participants, class_name: 'Participant'

  # Association through EmployerRecord
  has_many :employer_records
  has_many :indirect_participants, through: :employer_records, source: :participant

  # Association with Workers through direct_participants
  has_many :workers, through: :direct_participants

  # Other methods...
  def full_name
    "#{first_name} #{last_name}"
  end

  
  class Employer < ApplicationRecord
    # Associations and other methods as before...
  
    validate :unique_as_participant, if: -> { ssn_changed? || new_record? }
    validates :ssn, uniqueness: { allow_blank: true }, if: -> { ssn.present? }
    validates :tin, uniqueness: { allow_blank: true }, if: -> { tin.present? }
  
    private
    
    def unique_as_participant
      if Participant.exists?(ssn: ssn) && (id.blank? || Participant.where.not(id: id).exists?(ssn: ssn))
        errors.add(:ssn, 'A participant with the same SSN already exists')
      end
    end
  end
end