如何检查日期范围是否在Ruby中的另一个日期范围之间

Question

So I have a date range which may be something like ((Date.today - 90)..Date.today) and I want to check to see whether (Date.today - 90) is after the first value in another date range, and Date.today is before the final value in a date range. I've tried the following below

((Date.parse('25-12-2000')..(Date.parse('25-12-2020')).include?((Date.today - 90)..Date.today)

This returns false. I also get false if I replace include? with member? or cover?

How do I get this to return true? Syntax change or do I need to use a different method in Ruby?

Answer 1

You could use cover? to check if the date range covers both values:

range = Date.new(2000, 12, 25)..Date.new(2020, 12, 25)

range.cover?(Date.today - 90) && range.cover?(Date.today)
#=> true

or use begin and end if you have two ranges:

range = Date.new(2000, 12, 25)..Date.new(2020, 12, 25)
other = (Date.today - 90)..Date.today

range.cover?(other.begin) && range.cover?(other.end)
#=> true

Answer 2

I'd just check the first and last date against the range:

range = (Date.today - 90)..Date.today)
validation_range = ((Date.parse('25-12-2000')..(Date.parse('25-12-2020'))
range.first > validation_range && range.last < validation_range.last

You could break this down even further, rather just the first and last dates of each:

start_date = (Date.today - 90)
end_date = Date.today
start_validation = Date.parse('25-12-2000')
end_validation = Date.parse('25-12-2020')
start_date > start_validation && end_date < end_validation

I'm not sure the naming's ideal and you could trim this down to one line if you wanted, but hopefully this serves for illustrative purposes. Also, you might want to use >= and <= though I'm not sure of whether the dates are inclusive.

This would avoid any potentially expensive loops.

Hope that helps - let me know how you get on or if you have any questions!

Answer 3

When you have two ranges A = (a..b) and B = (y..z) and want to know if B is fully covered by A then you can just ask if:

a <= y && z <= b

No need to build the ranges upfront.