[Caution summary] Set Ruby time (Time type/Date type/DateTime type) in the column

Time type / Date type / DateTime type

Time type

--Class that handles date and time in UNIX time

irb(main):001:0> Time.now
=> 2021-01-02 01:41:25.0792755 +0000

Date type

--Class that handles dates

irb(main):004:0> Date.today
=> Sat, 02 Jan 2021

DateTime type

--Classes that handle dates and times --Since it is a subclass of Date, you can use Date methods.

irb(main):003:0> DateTime.now
=> Sat, 02 Jan 2021 01:41:40 +0000

validation --The usual method (the same method as integer type and string type) does not work. --You need to define your own method to add the error statement and set it as validation.

validate :day_after_today

def day_after_today
    errors.add(:food_date, 'Please enter a date in the past, including today') if !food_date.nil? && (food_date > Time.zone.today)
end

--Example of validation that will result in an error if you enter a date after tomorrow --valid, no s needed

Tokyo time setting

If you do not set the time_zone, it will be recorded in Coordinated Universal Time (UTC) by default.

module App
  class Application < Rails::Application
    config.time_zone = 'Tokyo'
  end
end

Comparison

--Comparison between Time type and DateTime type is in seconds --The following is an example when validation is applied so that the difference between DateTime type variables is 12 hours or more.

def time_before_give
  errors.add(:limit_time, 'Please enter the date and time 12 hours or more before the hem division time') if !limit_time.nil? && give_time - limit_time < 12 * 60 * 60
end

Column type change

--Since it is not possible to change from Time type to DateTime type, it is necessary to follow the procedure of "Delete column ⇨ Add column".