adopt-a-hydrant/app/models/reminder.rb

class Reminder < ActiveRecord::Base
  include ActiveModel::ForbiddenAttributesProtection
  belongs_to :from_user, class_name: 'User'
  belongs_to :thing
  belongs_to :to_user, class_name: 'User'
  validates :from_user, presence: true
  validates :thing, presence: true
  validates :to_user, presence: true
end