Parse a date with too many days in month - ruby-on-rails

Question

Is there any way to correctly parse a date that has too many days in the month? E.g.
'2016-01-32' = '2016-02-01'
'2015-12-32' = '2016-01-01'
This is to support easy date manipulation on some of my JS based front-end.
This is with Ruby 2.3.0 and Rails 4.2.5. I think this was working in an earlier release - perhaps the parsing rules were tightened?
I'd rather rely on a standard library and it's knowledge of leap years etc, rather than implementing this myself.

Answer 1

You can use Date::_parse (or Date::_iso8601) to parse a date string without validation:
require 'date'
h = Date._parse('2016-01-32')
#=> {:mday=>32, :year=>2016, :mon=>1}
And create a date instance using Simone Carletti's suggestion:
Date.new(h[:year], h[:mon]).next_day(h[:mday] - 1)
#=> #<Date: 2016-02-01 ...>
If both, days and months can be out of range, you could use:
h = Date._parse('2016-14-32')
#=> {:mday=>32, :year=>2016, :mon=>14}
Date.new(h[:year]).next_month(h[:mon] - 1).next_day(h[:mday] - 1)
#=> #<Date: 2017-03-04 ...>
next_day and next_month are equivalent to + and << respectively, so the last line can also be written as:
Date.new(h[:year]) << (h[:mon] - 1) + (h[:mday] - 1)
or:
Date.new(h[:year]) << h[:mon].pred + h[:mday].pred

Answer 2

require 'date'
y, m, d = '2016-01-32'.split('-').map(&:to_i)
# => [2016, 01, 32]
last_day_of_month = Date.civil(y, m, -1)
# => #<Date: 2016-01-31 ((2457419j,0s,0n),+0s,2299161j)>
date = last_day_of_month + (d - last_day_of_month.day)
# => #<Date: 2016-02-01 ((2457420j,0s,0n),+0s,2299161j)>

Answer 3

Trying to parse a date like the one you mentioned will raise an error
DateTime.parse('2016-01-32')
ArgumentError: invalid date
One possible solution is to create a custom function/class for date parsing. You forward the parse to the DateTime object, if it fails with that error, you can retry by stripping the day number and replacing it with 1.
If it succeeds, you add the remaining days to the date.
date = DateTime.parse('2016-01-1')
=> Fri, 01 Jan 2016 00:00:00 +0000
date + (32-1).days
=> Mon, 01 Feb 2016 00:00:00 +0000
No existing core or Rails library will do that automatically for you. Hence you need a custom function for that.
You should be able to easily write the method following the instructions and the example above.

Answer 4

Here is one way to do it:
require 'date'
date_string = '2016-01-50'
year,month,day = date_string.split('-').map(&:to_i)
date = Date.new(year,month)
(day-1).times{date = date.next}
p date #=> 2016-02-19