我们经常要用到时间的格式化，我们可以使用ri来看看reference doc.

ri Time.strftime

结果显示如下:

------------------------------------------------------- Time#strftime
                time.strftime( string ) => string
---------------------------------------------------------------------
    Formats _time_ according to the directives in the given format
    string. Any text not listed as a directive will be passed through
    to the output string.

    Format meaning:

      %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 data 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"

非常详细的参数文档。

我们在environment.rb里定义如下内容:

Time::DATE_FORMATS[:due_time] = "due at %B %d on %I:%M %p"

然后，我们就可以在页面中像使用to_s(:db)一样使用:due_time了:

<%= task.due_at.to_s(:due_time) %>