在Ruby on Rails中将DateTime转换为简单日期

Question

我在db中有一个datetime列,当我向用户显示时,我希望将其转换为一个简单的日期.

我怎样才能做到这一点？

def shown_date
  # to_date does not exist, but is what I am looking for
  self.date || self.exif_date_time_original.to_date 
end

Answer 1

DateTime#to_date 与ActiveSupport一起存在:

$ irb
>> DateTime.new.to_date
NoMethodError: undefined method 'to_date' for #<DateTime: -1/2,0,2299161>
    from (irb):1

>> require 'active_support/core_ext'
=> true

>> DateTime.new.to_date
=> Mon, 01 Jan -4712

Answer 2

你好collimarco :)你可以使用ruby strftime方法来创建你自己的日期/时间显示.

time.strftime(string)=> string

  %a - The abbreviated weekday name (``Sun'')
  %A - The  full  weekday  name (``Sunday'')
  %b - The abbreviated month name (``Jan'')
  %B - The  full  month  name (``January'')
  %c - The preferred local date and time representation
  %d - Day of the month (01..31)
  %H - Hour of the day, 24-hour clock (00..23)
  %I - Hour of the day, 12-hour clock (01..12)
  %j - Day of the year (001..366)
  %m - Month of the year (01..12)
  %M - Minute of the hour (00..59)
  %p - Meridian indicator (``AM''  or  ``PM'')
  %S - Second of the minute (00..60)
  %U - Week  number  of the current year,
          starting with the first Sunday as the first
          day of the first week (00..53)
  %W - Week  number  of the current year,
          starting with the first Monday as the first
          day of the first week (00..53)
  %w - Day of the week (Sunday is 0, 0..6)
  %x - Preferred representation for the date alone, no time
  %X - Preferred representation for the time alone, no date
  %y - Year without a century (00..99)
  %Y - Year with century
  %Z - Time zone name
  %% - Literal ``%'' character

   t = Time.now
   t.strftime("Printed on %m/%d/%Y")   #=> "Printed on 04/09/2003"
   t.strftime("at %I:%M%p")            #=> "at 08:56AM"

Answer 3

在Ruby 1.9.2及更高版本中,他们向DateTime添加了一个.to_date函数:

http://ruby-doc.org/stdlib-1.9.2/libdoc/date/rdoc/DateTime.html#method-i-to_date

此实例方法似乎不存在于1.8.7之类的早期版本中.