How to Calculate the Day of the Week of a Date in Ruby

How can I calculate the day of the week of a date in ruby?

I have used this because I hated to go to the Date docs to look up the strftime syntax, not finding it there and having to remember it is in the Time docs.

require 'date'

class Date
  def dayname
     DAYNAMES[self.wday]
  end

  def abbr_dayname
    ABBR_DAYNAMES[self.wday]
  end
end

today = Date.today

puts today.dayname
puts today.abbr_dayname

How to get the date by day of the week ruby

To get the current day in Rails, you can use:

Date.today

To get the previous Saturday (since today is Monday 3rd July, that's Saturday 1st July), you can use:

Date.today.beginning_of_week(:saturday)

Or, if what you actually wanted was the previous week's Saturday (Saturday 24th June), then you can use:

Date.today.weeks_ago(1).beginning_of_week(:saturday)

Or, if you prefer:

1.week.ago.beginning_of_week(:saturday)

...However, note that the above will return an ActiveSupport::TimeWithZone object rather than a Date object - so will behave slightly differently.

Have a read through the rails documentation - in particular, the ActiveSupport extensions to ruby's Date class to see what methods are available.

If, for some reason, you needed to do this in pure ruby (i.e. without the above mentioned ActiveSupport extensions that come bundled with rails), then you could instead utilise the Date.parse method:

require 'date'

Date.parse("Saturday") - 7
  # => Sat, 01 Jul 2017

---

In order to convert your Date (or similar) object to the string format you desire ("24-June-2017"), you can use ruby's strftime method:

(Date.parse("Saturday") - 7).strftime('%d-%B-%Y')

In rails, it is a common convention to place such custom date formats in a locale or initializer to avoid repetition. You can then reference this format by name:

# config/initializers/date_formats.rb
# (Call this whatever you want!)
Date::DATE_FORMATS[:calendar] = '%d-%B-%Y'

# Anywhere else in the rails app
Date.today.beginning_of_week(:saturday).to_s(:calendar)
  # => "01-July-2017"

Rails - Determine the day of the week

In Ruby 2.1.1, the Date class has a friday? method

Returns true if the date is a friday

First, require the date library

require 'date'

Then create a new date instance with the current date. Here's an example

current_time = Time.now
year = current_time.year
month = current_time.month
day = current_time.day

date = Date.new(year, month, day)
date.friday?
=> true

Depending on your coding preferences, you could DRY this up even more

date = Date.new(Time.now.year, Time.now.month, Time.now.day)
=> #<Date: 2016-03-11 ((2457459j,0s,0n),+0s,2299161j)>
date.friday?

If you'd like to solve this without a Boolean method, (the ones that usually end in a question mark and return either true or false), such as when you're comparing to a database column, you can use the Date#wday method. Keep in mind, this returns a number in the range (0..6) with 0 representing Sunday. This means that you want to pass in 5 to check for Friday.

if date.wday == 5
  // Do something
end

Also, if you are working with business hours, it might be easiest to use the business_time gem

You can also include the holidays gem with business_time.

First, install the gems

gem install business_time
gem install holidays

Then require the gem

require 'business_time'
require 'holidays'

Find out if today is a workday

Date.today.workday?

and is a holiday

You can now use something like this to determine if today is a holiday

Holidays.on(date, :us).empty?

and is between office working hours

The definition of office hours varies from person to person. There's no set-in-stone answer. However, with the business_time gem, you can set configurations

BusinessTime::Config.beginning_of_workday = "8:30 am"
BusinessTime::Config.end_of_workday = "5:30 pm"

Sources

Ruby

http://ruby-doc.org/stdlib-2.1.1/libdoc/date/rdoc/Date.html#method-i-wday

http://ruby-doc.org/stdlib-2.1.1/libdoc/date/rdoc/Date.html#method-i-friday-3F

Gems

https://github.com/bokmann/business_time

https://github.com/holidays/holidays

How do I get day of the week from a date object?

Looking at the Ruby docs for strftime

Time.now.strftime("%A, %d/%m/%Y")
=> "Wednesday, 04/01/2012"

The %A character is the full day name.

Ruby code to get the date of next Monday (or any day of the week)

require 'date'

def date_of_next(day)
  date  = Date.parse(day)
  delta = date > Date.today ? 0 : 7
  date + delta
end

Date.today
#=>#<Date: 2011-10-28 (4911725/2,0,2299161)>
date_of_next "Monday"
#=>#<Date: 2011-10-31 (4911731/2,0,2299161)>
date_of_next "Sunday"
#=>#<Date: 2011-10-30 (4911729/2,0,2299161)>

Ruby find next Thursday (or any day of the week)

DateTime.now.next_week.next_day(3)

As @Nils Riedemann pointed out:

Keep in mind that it will not get the next thursday, but the thursday
of the next week. eg. If tomorrow was thursday, it won't return
tomorrow, but next week's thursdays.

Here is an excerpt of some code I've written recently which handles the missing case.

require 'date'

module DateTimeMixin

  def next_week
    self + (7 - self.wday)
  end

  def next_wday (n)
    n > self.wday ? self + (n - self.wday) : self.next_week.next_day(n)
  end

end

# Example

ruby-1.9.3-p194 :001 > x = DateTime.now.extend(DateTimeMixin)
 => #<DateTime: 2012-10-19T15:46:57-05:00 ... > 

ruby-1.9.3-p194 :002 > x.next_week
 => #<DateTime: 2012-10-21T15:46:57-05:00 ... > 

ruby-1.9.3-p194 :003 > x.next_wday(4)
 => #<DateTime: 2012-10-25T15:46:57-05:00 ... > 

How to get the date of this Wednesday , this Thursday etc. in Rails

You could use #next_occurring

pry(main)> Time.zone.today.beginning_of_week
Mon, 20 Jan 2020
pry(main)> Time.zone.today.beginning_of_week.next_occurring(:thursday)
Thu, 23 Jan 2020

Given date and day in week, find the closest date in future

This is a pure Ruby solution.

require 'date'

d = Date.strptime('9-4-2016', '%d-%m-%Y')
  #=> #<Date: 2016-04-09 ((2457488j,0s,0n),+0s,2299161j)> 
d + (1 - d.wday) % 7
  #=> #<Date: 2016-04-11 ((2457490j,0s,0n),+0s,2299161j)> 

1 is Monday's offset. d.wday #=> 6.

I have assumed that if the date falls on a Monday, the "closest" Monday is the same day. If it is to be the following Monday, use:

d + (d.wday == 1) ? 7 : (1 - d.wday) % 7

How can I display the days of the week?

You can use a range and iterate through:

<% (Date.today.beginning_of_week(:sunday)...Date.today.end_of_week).each do |date| %>
  <p><%= date.strftime('%a %d') %></p>
<% end %>

Will give you:

<p>Sun 28</p>
<p>Mon 29</p>
<p>Tue 30</p>
<p>Wed 01</p>
<p>Thu 02</p>
<p>Fri 03</p>
<p>Sat 04</p>

Note that we're using ... instead of .. for the range.

How can I output the day of week with embedded ruby?

Say i have date = Time.now.to_date then date.strftime("%A") will print name for the day of the week and to have just the number for the day of the week write date.wday.

Copy from here

So Time.now.strftime("%A") and in your case

<h6>
  <%= Time.now.strftime("%A, %B %d. %Y") %>
</h6>

Easiest to test this is the rails c. To remove the leading zero on the %d use %-d instead.

---

Related Topics