Question

I have two models Appointment and Schedule, in Appointment I have a time field called adate and in schedule I have start_time and end end_time fields.

I want to compare the value in adate with the the values within start_time and end_time to see if is possible to make the appointment at that hour.

How can I compare those values?

  create_table "appointments", :force => true do |t|
    t.integer  "doctor_id"
    t.date     "adate"
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
    t.time     "atime"
  end

  create_table "schedules", :force => true do |t|
    t.string   "day"
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
    t.integer  "doctor_id"
    t.time     "start_time"
    t.time     "end_time"
  end

It should be a validation but should I implement this?

Model

class Appointment < ActiveRecord::Base
  attr_accessible :adate, :atime, :doctor_id  
  validates :adate, :presence => true     
  belongs_to :doctor
  validates_date :adate, :after => lambda { Date.current }  
end

class Schedule < ActiveRecord::Base
  attr_accessible :doctor_id, :day, :end_time, :start_time  
  belongs_to :doctor
end

Answer 1

From http://guides.rubyonrails.org/active_record_validations_callbacks.html#custom-methods, you can see how to write arbitrary methods for validation.

In your case, you would probably write something of this form.

class Appointment < ActiveRecord::Base
    # ... All the other stuff
    validate :appointment_time_is_valid_for_day

    def appointment_time_is_valid_for_day
        # TODO: Get the schedule for that day/doctor.
        unless schedule.start_time <= atime and
          atime <= schedule.end_time
            errors.add(:atime, "Doctor's not in at this time")
        end
    end
end

This assumes that you already have some way to get the schedule of the doctor on the day of the appointment. I don’t know enough about your models to tell you how to do this.