Rails：X为true时发送邮件的最简单方法

Question

So I've been looking for the simplest way to send an e-mail when X column of Payments table in the database is == 'condition'. Basically what I want is to add a payment and set a date like 6 months. When 6 months have passed I want to send the mail. I've seen many solutions like using Whenever cron jobs and others but I want to know the absolute simplest way (perhaps using Rails only without relying on outside source) to keep my application light and clean. I was thinking I could use the auto generated created_at to evaluate when x time has passed.

Answer 1

The "easiest" way is to use Active Job in conjunction with a state machine:

EmailJob.set(wait: 6.months).perform_later(user.id) if user.X_changed?

The problem with this is that the queue will accumulate jobs since jobs don't get handled right away. This may lead to other performance issues since there are now more jobs to scan and they're taking up more memory.

Cron jobs are well suited for this kind of thing. Depending on your hosting platform, there may be various other ways to handle this; for example, Heroku has Heroku Scheduler.

There are likely other ways to schedule repeating tasks without cron, such as this SO answer .

edit: I did use a gem once called 'fist_of_fury', but it's not currently maintained and I'm not sure how it would perform in a production environment. Below are some snippets for how I used it in a rails project:

in Gemfile

gem 'fist_of_fury'

in config/initializers/fist_of_fury.rb

# Ensure the jobs run only in a web server.
if defined?(Rails::Server)
  FistOfFury.attack! do
    ObserveAllJob.recurs { minutely(1) }
  end
end

in app/jobs/observe_all_job.rb

class ObserveAllJob
  include SuckerPunch::Job
  include FistOfFury::Recurrent

  def perform
    ::Task.all.each(&:observe)
  end
end

Answer 2

Since you have a column in your db for the time to send email, make it a datetime datatype and you can set the email date as soon as the event payment event is created. Then, you can have a rake task where,

range = Time.now.beginning_of_day..Time.now.end_of_day
Payment.where(your_datetime_custom_column: range).each do |payment|
  payment.user.send_email
end

and you can run this task everyday from the scheduler.