Ruby hash string with dates - ruby

Question

Im working on a birthday widget, that shows the name of the person who is the closest to have his birthday.
I currently have the following code;
<%
def closest_birthdate(birthdates)
sorted_dates = birthdates.sort_by do |_, value|
(DateTime.parse(value) - DateTime.now).abs
end
name, birthday = sorted_dates.first
"#{name} has his birthday on #{Date.parse(birthday).strftime('%m-%d')}"
end
%>
<% hash = { 'Bart' => '2017-12-06',
'Thomas' => '2017-10-06',
'William' => '2018-09-05',} %>
<%= closest_birthdate(hash) %>
It returns the following:
Thomas has his birthday on 10-06
Now, after his birthday, I have to change the year from 2017 to 2018.
The dates with names are currently stored as strings.
How can I change the strings to dates?
How can I use their actual birth dates so I dont have to change the year from 2017 to 2018 everytime they had their birthday?

Answer 1

Storing dates
A Date instance can be created via Date::new:
require 'date'
birthdate = Date.new(1978, 12, 6)
#=> #<Date: 1978-12-06 ...>
Calculating the next birthday
The next or upcoming birthday for the above birthdate is 2017-12-06, so we have to combine today's year and the birthdate's month and day:
today = Date.today
#=> #<Date: 2017-10-06 ...>
next_birthday = Date.new(today.year, birthdate.month, birthdate.day)
#=> #<Date: 2017-12-06 ...>
What happens if the birthday already occurred this year?
birthdate = Date.new(1985, 9, 5)
#=> #<Date: 1985-12-06 ...>
next_birthday = Date.new(today.year, birthdate.month, birthdate.day)
#=> #<Date: 2017-09-05 ...>
To actually get the next birthday, we have to add a year in that case: (i.e. if next_birthday happens to be before today)
next_birthday = next_birthday.next_year if next_birthday < today
#=> #<Date: 2018-09-05 ...>
Finding the closest birthday
Let's move the above calculation into a method:
def next_birthday(birthdate, today = Date.today)
date = Date.new(today.year, birthdate.month, birthdate.day)
date < today ? date.next_year : date
end
To find the closest (upcoming) birthday, we can either use sort_by and first:
hash = {
'Bart' => Date.new(1978, 12, 6),
'Thomas' => Date.new(1981, 10, 6),
'William' => Date.new(1985, 9, 5)
}
hash.sort_by { |_name, birthdate| next_birthday(birthdate) }
#=> [
# ["Thomas", #<Date: 1981-10-06 ...>],
# ["Bart", #<Date: 1978-12-06 ...>],
# ["William", #<Date: 1985-09-05 ...>]
# ]
hash.sort_by { |_name, birthdate| next_birthday(birthdate) }.first
#=> ["Thomas", #<Date: 1981-10-06 ...>]
or min_by:
hash.min_by { |_name, birthdate| next_birthday(birthdate) }
#=> ["Thomas", #<Date: 1981-10-06 ...>]
Generating output
name, birthdate = hash.min_by { |_name, birthdate| next_birthday(birthdate) }
puts "#{name}'s birthday is on #{birthdate.strftime('%m-%d')}"
# Thomas's birthday is on 10-06
We could also add the age:
age = next_birthday(birthdate).year - birthdate.year
#=> 36
puts "#{name} is turning #{age} on #{birthdate.strftime('%m-%d')}"
# Thomas is turning 36 on 10-06
Edge case
February 29 only occurs on leap years:
Date.new(1984, 2, 29)
#=> #<Date: 1984-02-29 ...>
Attempting to create a February 29 on a non-leap year results in an error:
Date.new(2017, 2, 29)
#=> ArgumentError: invalid date
You could remove those dates or adjust them unless today's year is leap? (to Feb 28 or Mar 1).

Answer 2

There is no standard object as a (birth)day without specification of the year. So you should just save an array of month and day of month. And it is much better to save them as integers rather than strings.
hash = {
'Bart' => [12, 6],
'Thomas' => [10, 6],
'William' => [9, 5],
}
To convert them to a date with a year specification (let's say year = 2018), do like this:
require "date"
date = Date.new(year, *hash['Bart']) rescue nil
Implementing it fully would be like this:
require "date"
def closest_birthdate(birthdates)
year, month, day = Date.today.year, Date.today.month, Date.today.day
name, (m, d) =
birthdates
.sort_by(&:last)
.bsearch{|_, (m, d)| month <= m and day < d}
return unless Date.new(year, m, d) rescue nil
"#{name} has his birthday on #{year}-#{m}-#{d}"
end
closest_birthdate(hash)

Answer 3

Try this if you don't want to change the structure:
<%
def closest_birthdate(birthdates)
sorted_dates = birthdates.sort_by do |_, value|
array = value.split("-") # you got something like this [2017, 12, 06]
(DateTime.parse("#{DateTime.now.year}-#{array[1]}-#{array[2]}") - DateTime.now).abs
end
name, birthday = sorted_dates.first
"#{name} has his birthday on #{Date.parse(birthday).strftime('%m-%d')}"
end
%>
<% hash = { 'Bart' => '1978-12-06',
'Thomas' => '1972-10-06',
'William' => '1992-09-05',} %>
<%= closest_birthdate(hash) %>
Hope this helps.