Question

我需要以最后两个星期日2014-01-20的格式计算。

所以，last_sunday = 2014-01-20和most_recent_sunday = 2014-01-26。

我正在使用Rails 4.0和Ruby 2.0。我怎样才能得到这些日期？

Answer 1

在rails 4中：

most_recent_sunday = Time.now.sunday.to_s

last_sunday =        Time.now.last_week.sunday.to_s

要使其符合您的格式：

DateTime.parse(most_recent_sunday).strftime("%Y-%m-%d")

http://apidock.com/rails/v4.0.2/DateAndTime/Calculations/sunday http://apidock.com/rails/v4.0.2/DateAndTime/Calculations/last_week

Answer 2

我建议你看看chronic gem

require 'chronic'
Chronic.parse("last sunday")
=> 2014-01-26 12:00:00 +0200

您还可以使用rail的active_support从上面计算的日期中减去7.days =）

Answer 3

[11] pry(main)> last_sunday = Time.now - (Time.now.wday + 7) * 86400
=> 2014-01-19 17:17:19 -0600
[12] pry(main)> most_recent_sunday = Time.now - (Time.now.wday) * 86400
=> 2014-01-26 17:18:03 -0600

Answer 4

纯Ruby解决方案：

require 'date'

last_two_weeks   = (Date.today-13)..Date.today
last_two_sundays = last_two_weeks.select &:sunday?

puts last_two_sundays #=> 2014-01-19, 2014-01-26

Ruby年 - 月 - 上周日的日期

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