在Ruby on Rails中将DateTime转换为简单的日期

Question

我在db中有一个datetime列，当我向用户展示它时，我想将其转换为简单的日期。

我该怎么做？

 
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不具有的ActiveSupport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 :)你可以使用红宝石的strftime方法来创建自己的乌尔日期/时间显示。

time.strftime（串）=>字符串

%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

我最近写了一个宝石来简化这一过程，并neaten了你的观点，等等等等

瞧瞧吧： http://github.com/platform45/easy_dates

Answer 4

在Ruby 1.9.2和上述他们增加了.to_date函数为DateTime：

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像1.8.7这样的早期版本中。

Answer 5

尝试先将条目转换为字符串。只要数据库列类型是一个日期，它就会被格式化为日期。

self.date || self.exif_date_time_original.to_s

Answer 6

对于老红宝石（1.8.x的）：

myDate = Date.parse(myDateTime.to_s)