If I have a specific date and then add a duration to it resulting in another date
For example:
d1 = Date.parse('1996-02-17')
d2 = d1 + 67.years + 3.months # 2063-05-17
Then, how can I get the difference between those dates back (in years and months in this case), because if I do something like
ActiveSupport::Duration.build(d2.to_time - d1.to_time)
then it produces 67 years, 2 months, 4 weeks, 20 hours, 5 minutes, and 24.0 seconds. I could try rounding it off etc, but that seems messy.
I don't necessarily have to use Duration for this. Is there any way to add/subtract spans of time in Ruby on Rails in such a way that the addition and subtraction are each other's inverse?
The issue arises because when you subtract two Time objects, it returns the difference as an exact ActiveSupport::Duration, which accounts for the varying lengths of months, weeks, and days.
If you want a simplified representation, like "67 years and 3 months", you can manually calculate the differences in years and months rather than relying on ActiveSupport::Duration.build.
Here's a way to achieve your desired output:
d1 = Date.parse('1996-02-17')
d2 = d1 + 67.years + 3.months
years = d2.year - d1.year
months = d2.month - d1.month
# Adjust if d2's month is before d1's month
if months < 0
years -= 1
months += 12
end
puts "#{years} years and #{months} months"