ruby - 如何查找到目前为止一周或一个月内的日期

Question

如何找到迄今为止一周或一个月内的日期。

days_for_week should return 19,20,21 (assuming current date is 21st)
days_for_month should return 1..21 (assuming current date is 21st)

Answer 1

首先，您可以使用Time.now.wday获取当前工作日，然后减去这将为您提供本周开始的日期。

对于第二个，它更简单，每个月都以 开头1st，对吗？

Answer 2

假设我正确阅读了您的问题...

第二个很简单：

def days_for_month
  1..Date.today.day
end

第一个需要一个小算法才能追溯到星期六：

def days_for_week
  days = []
  day = Date.today
  until day.saturday?
    days.unshift(day.day)
    day -= 1
  end
  days
end

Answer 3

主动支持提供了很多有用的方法，例如at_beginning_of_week、at_end_of_week、 at_beginning_of_month 等。

> Date.today.at_beginning_of_week
=> Mon, 20 May 2013

对于这种特殊情况，您可以这样做

> (Date.today.at_beginning_of_week..Date.today).map &:day
=> [20, 21]

相似地

> (Date.today.at_beginning_of_month..Date.today).map &:day
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21]

或者干脆

> 1..Date.today.day