In Rails, display time between two dates in English

Question

In a Rails project I want to find the difference between two dates and then display it in natural language. Something like

>> (date1 - date2).to_natur         


        

Answer 1

distance_of_time_in_words is the most accurate here. Daniel's answer is actully wrong: 2.5 years ago should produce exactly 2 years, 6 months. The issue is that months contain 28-31 day, and years might be leap.

I wish I knew how to fix this :(

Answer 2

I tried Daniel's solution and found some incorrect results for a few test cases, due to the fact that it doesn't correctly handle the variable number of days found in months:

> 30.days < 1.month
   => false

So, for example:

> d1 = DateTime.civil(2011,4,4)
> d2 = d1 + 1.year + 5.months
> time_diff_in_natural_language(d1,d2)
=> "1 year, 5 months, 3 days" 

The following will give you the correct number of {years,months,days,hours,minutes,seconds}:

def time_diff(from_time, to_time)
  %w(year month day hour minute second).map do |interval|
    distance_in_seconds = (to_time.to_i - from_time.to_i).round(1)
    delta = (distance_in_seconds / 1.send(interval)).floor
    delta -= 1 if from_time + delta.send(interval) > to_time
    from_time += delta.send(interval)
    delta
  end
end
> time_diff(d1,d2)
 => [1, 5, 0, 0, 0, 0] 

Answer 3

The Rails' ActionView module includes two methods that may do what you require:

• distance_of_time_in_words
• distance_of_time_in_words_to_now

Answer 4

def date_diff_in_natural_language(date_from, date_to)
  components = []
  %w(years months days).each do |interval_name|
    interval = 1.send(interval_name)
    count_intervals = 0
    while date_from + interval <= date_to
      date_from += interval
      count_intervals += 1
    end
    components << pluralize(count_intervals, interval_name) if count_intervals > 0
  end
  components.join(', ')
end

Answer 5

The other answers may not give the type of output that you're looking for, because instead of giving a string of years, months, etc., the Rails helpers just show the largest unit. If you're looking for something more broken down, here's another option. Stick this method into a helper:

def time_diff_in_natural_language(from_time, to_time)
  from_time = from_time.to_time if from_time.respond_to?(:to_time)
  to_time = to_time.to_time if to_time.respond_to?(:to_time)
  distance_in_seconds = ((to_time - from_time).abs).round
  components = []

  %w(year month week day).each do |interval|
    # For each interval type, if the amount of time remaining is greater than
    # one unit, calculate how many units fit into the remaining time.
    if distance_in_seconds >= 1.send(interval)
      delta = (distance_in_seconds / 1.send(interval)).floor
      distance_in_seconds -= delta.send(interval)
      components << pluralize(delta, interval)
      # if above line give pain. try below one  
      # components <<  interval.pluralize(delta)  
    end
  end

  components.join(", ")
end

And then in a view you can say something like:

<%= time_diff_in_natural_language(Time.now, 2.5.years.ago) %>
=> 2 years, 6 months, 2 days 

The given method only goes down to days, but can be easily extended to add in smaller units if desired.

Answer 6

DateHelper#distance_of_time_in_words