Rails 3.2：Ruby日期逻辑

Question

I have a rails app where I need to check date(s)(dd/mm) from several models in my database and trigger a mailer 2 weeks before, 1 week before, and 1 day before each date. How could I write this logic in my app (rails 3.2)?

*Note - I plan on using a rake task to check whether and mails need to be sent out.

Answer 1

You could do this with scopes:

class MyModel < ActiveRecord::Base
  scope :two_weeks_before, lambda{|the_date| where('my_date between ? and ?', 2.weeks.until(the_date), the_date)}
  scope :one_week_before, lambda{|the_date| where('my_date between ? and ?', 1.week.until(the_date), the_date)}
  scope :the_day_before, lambda{|the_date| where('my_date between ? and ?', 1.day.until(the_date), the_date)}
  scope :undelivered, where(:delivered => false)
end

# usage:
MyModel.two_weeks_before(Date.tomorrow).undelivered.all.each do |model|
  MyMailer.notification(model).deliver
  model.update_attribute(:delivered, true)
end

The date ranges grab all models with a date in the 2 weeks before, you can adjust the endpoints as necessary, obv.

Answer 2

2 weeks before, compare date with this:

Model.where("my_date between ? and ?", Date.today - 15, Date.today - 14)

1 week, to this:

Model.where("my_date between ? and ?", Date.today - 8, Date.today - 7)

Try in your console and see the results.