使用 Epoch 时间戳创建活动模型日期时间

Question

我有一个移动应用程序，它可以通过使用SimpleEvent 模型的标准路由向我们的 Rails 应用程序发送 Post 请求来创建事件。模型的重要部分在模式中如下所示：

create_table "simple_events", force: true do |t|
    t.datetime "start_date",   null: false
    t.datetime "end_date",     null: false
end

应用程序发送浮点值来指示时间是最简单的，因为这是它们在本地存储的方式。但是，当我尝试使用带有以下行的纪元时间戳在 Rails 控制台中创建 SimpleEvent 时：

SimpleEvent.create("start_date"=> 1406815132.0, "end_date"=> 1406815132.0)

我收到此错误：

ArgumentError: argument out of range
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activesupport-4.1.4/lib/active_support/values/time_zone.rb:289:in `initialize'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activesupport-4.1.4/lib/active_support/values/time_zone.rb:289:in `new'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activesupport-4.1.4/lib/active_support/values/time_zone.rb:289:in `parse'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activesupport-4.1.4/lib/active_support/core_ext/string/zones.rb:9:in `in_time_zone'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.4/lib/active_record/attribute_methods/time_zone_conversion.rb:37:in `start_date='
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.4/lib/active_record/attribute_assignment.rb:45:in `public_send'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.4/lib/active_record/attribute_assignment.rb:45:in `_assign_attribute'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.4/lib/active_record/attribute_assignment.rb:32:in `block in assign_attributes'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.4/lib/active_record/attribute_assignment.rb:26:in `each'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.4/lib/active_record/attribute_assignment.rb:26:in `assign_attributes'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.4/lib/active_record/core.rb:455:in `init_attributes'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.4/lib/active_record/core.rb:198:in `initialize'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.4/lib/active_record/inheritance.rb:30:in `new'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.4/lib/active_record/inheritance.rb:30:in `new'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/activerecord-4.1.4/lib/active_record/persistence.rb:33:in `create'
    from (irb):71
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/railties-4.1.4/lib/rails/commands/console.rb:90:in `start'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/railties-4.1.4/lib/rails/commands/console.rb:9:in `start'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/railties-4.1.4/lib/rails/commands/commands_tasks.rb:69:in `console'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/railties-4.1.4/lib/rails/commands/commands_tasks.rb:40:in `run_command!'
    from /Users/ataylor/.rvm/gems/ruby-2.1.1/gems/railties-4.1.4/lib/rails/commands.rb:17:in `<top (required)>'
    from bin/rails:4:in `require'
    from bin/rails:4:in `<main>'2.1.1 :072 >

我尝试在 rails 源代码中寻找可能的解释，但运气不佳。我可以做些什么来允许从模型中的时间戳创建 DateTimes？

Answer 1

如果您仍然希望能够将start_date 和end_date 与正常时间对象或字符串一起使用，我将创建几个新方法来从时间字符串设置 start_date/end_date：

class SimpleEvent < ActiveRecord::Base
  def start_ts=(ts)
    write_attribute :start_date, DateTime.strptime(ts.to_s, '%s')
  end

  def end_ts=(ts)
    write_attribute :end_date, DateTime.strptime(ts.to_s, '%s')
  end
end

使用它们：

SimpleEvent.create("start_ts"=>"1406815132.0", "end_ts"=>"1406815132.0")

现在，当您使用 start_ts/end_ts 方法创建 SimpleEvent 时，它将解析时间戳并适当地设置 start_date/end_date。

Answer 2

我建议通过添加一个额外的函数将它转换为日期时间并存储来保存日期时间。

class SimpleEvent < ActiveRecord::Base

  def self.save_time start_time, end_time
      self.create(start_time: Time.at(start_time).to_datetime, end_time: Time.at(end_time).to_datetime
  end
end

我们关心在模型本身中编写一个函数，以便我们可以将数据作为纪元时间本身读取。

class SimpleEvent < ActiveRecord::Base

   def started_at
      self.start_time.to_i
   end

   def end_at
      self.end_time.to_i
   end
end