如何查找到目前爲止一週或一個月內的日期

Question

如何查找到目前爲止一週或一個月內的日期。

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

主動支持提供了很多有用的方法，如at_beginning_of_week,at_end_of_week，at_beginning_of_month等。

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

對於這個特殊的情況下，你可以做

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

同樣

> (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] 

或者乾脆

> 1..Date.today.day 

Answer 2

對於第一個，你可以使用Time.now.wday得到當前一週的一天，然後減去會給你這一週的開始日期。

對於第二個，它更簡單，每個月以1st開頭，對吧？

Answer 3

假設我在正確閱讀您的問題...

第二個很簡單：

def days_for_month 
    1..Date.today.day 
end 

首先需要一點點的算法來背到星期六工作：

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