How do you say something happened “x minutes ago”

问题:

If I have a time variable in Ruby, how could I say that it refers to an event that happened one of the following:

"x minutes ago" or "x hours ago" or "x days ago"

Obviously if something happened 2 days ago, I would not want to say it happened such-and-such minutes ago.

回答1:

If you are on rails:

time_ago_in_words

回答2:

Here's the language agnostic version which you should be able to convert into any language:

ONE_MINUTE = 60
ONE_HOUR = 60 * ONE_MINUTE
ONE_DAY = 24 * ONE_HOUR
ONE_WEEK = 7 * ONE_DAY
ONE_MONTH = ONE_DAY * 3652425 / 120000
ONE_YEAR = ONE_DAY * 3652425 / 10000

def when(then):
    seconds_ago = now() - then

    if seconds_ago < 0:
        return "at some point in the future (???)"
    if seconds_ago == 0:
        return "now"

    if seconds_ago == 1:
        return "1 second ago"
    if seconds_ago < ONE_MINUTE:
        return str(seconds_ago) + " seconds ago"

    if seconds_ago < 2 * ONE_MINUTE:
        return "1 minute ago"
    if seconds_ago < ONE_HOUR:
        return str(seconds_ago/ONE_MINUTE) + " minutes ago"

    if seconds_ago < 2 * ONE_HOUR:
        return "1 hour ago"
    if seconds_ago < ONE_DAY:
        return str(seconds_ago/ONE_HOUR) + " hours ago"

    if seconds_ago < 2 * ONE_DAY:
        return "1 day ago"
    if seconds_ago < ONE_WEEK:
        return str(seconds_ago/ONE_DAY) + " days ago"

    if seconds_ago < 2 * ONE_WEEK:
        return "1 week ago"
    if seconds_ago < ONE_MONTH:
        return str(seconds_ago/ONE_WEEK) + " weeks ago"

    if seconds_ago < 2 * ONE_MONTH:
        return "1 month ago"
    if seconds_ago < ONE_YEAR:
        return str(seconds_ago/ONE_MONTH) + " months ago"

    if seconds_ago < 2 * ONE_YEAR:
        return "1 year ago"
    return str(seconds_ago/ONE_YEAR) + " years ago"

Note that the year/month figures are approximate (based on averages) but that shouldn't really matter since the relative error will still be very low.

回答3:

You need to do something like this:

tnow = Time.now
elapsed = tnow - tevent # elapsed time in seconds

if (elapsed < 60)
  puts "#{elapsed} seconds ago"
elsif (elapsed < 60*60)
  puts "#{elapsed/60} minutes ago"
end

回答4:

Here is a complete example if you choose to go outside of full Rails but are willing to use active_support (gem install actionview)

#!/usr/bin/env ruby

require 'active_support'
require 'active_support/core_ext/object/acts_like'
require 'active_support/core_ext/time/acts_like'
require 'action_view'

require 'date'

# Avoid a deprecation warning
I18n.enforce_available_locales = false

# Add time_ago_in_words
extend ActionView::Helpers::DateHelper

[
  '2014-04-24 16:20:00',
  '2014-04-21 16:20:00',
  '2014-03-24 16:20:00',
  '2013-04-20 16:20:00',
].map {|t| DateTime.parse t}.each do |time|
  puts time_ago_in_words time
end

At time of writing, this outputs:

about 6 hours
3 days
about 1 month
about 1 year