Date validation in Ruby - ruby-on-rails

Question

How to check if the date is valid date in ruby. Many of the methods are check only the range. But, I need to check the date with day of
week to check whether the date is valid or not. For Ex:
20 Jul 2016 Wed --> Valid
20 Jul 2016 Mon --> Not-Valid
How to do this in ruby ?

Answer 1

I'm not pretend on the best solution ever, but this should work.
def valid_date?(date)
Date.parse(date).strftime("%d %b %Y %a") == date
end
[55] pry(main)> valid_date?("20 Jul 2016 Wed")
=> true
[56] pry(main)> valid_date?("20 Jul 2016 Mon")
=> false
[57] pry(main)>
If you have many formats you may pass format as a second argument
def valid_date?(date, fmt)
Date.parse(date).strftime(fmt) == date
end
=> :valid_date?
[59] pry(main)> valid_date?("20 Jul 2016 Wed", "%d %b %Y %a")
=> true
Hope this will help.
UPDATE
As I mentioned in comment that method name overlaps with existing method valid_date?
So, you may just rename the custom method
def date_valid?(date, fmt)
Date.parse(date).strftime(fmt) == date
end
[2] pry(main)> date_valid?("20 Jul 2016 Wed", "%d %b %Y %a")
=> true

Answer 2

Just out of curiosity:
dates = ['20 Jul 2016 Wed', '20 Jul 2016 Mon']
dates.map do |date|
Date.parse(date).public_send(
Date.instance_methods.detect do |m|
m.to_s =~ /\A#{date[-3..-1].downcase}.*day\?\z/
end)
end
#⇒ [ true, false ]

Answer 3

require 'date'
dates = ['20 Jul 2016 Wed', '20 Jul 2016 Mon']
dates.select do |s|
d = Date.strptime(s[0,11], "%d %b %Y") rescue nil
d.nil? ? false : (Date::ABBR_DAYNAMES[d.wday] == s[-3,3])
end
#=> ["20 Jul 2016 Wed"]
This reads, "select strings 'dd mmm yyyy' that represent valid dates and whose day-of-week matches the day-of-week given by the last three characters of the string".