Working with Dates

in
Ruby on Rails







Nick Nguyen

@thenicknguyen

Ruby Date/Time


 $ irb
 > Date.new
  => #<Date: -4712-01-01 ((0j,0s,0n),+0s,2299161j)>
 > Time.new
  => 2013-11-10 20:43:21 -0600
 > DateTime.new
  => #<DateTime: -4712-01-01T00:00:00+00:00 ((0j,0s,0n),+0s,2299161j)>

Strftime



 > Date.today.strftime("%B %d, %Y")    => "November 11, 2013"
 > Date.today.strftime("%m/%d/%y")     => "11/11/13"
 > DateTime.now.strftime("%H:%M")      => "13:06"

Date.parse



 > Date.parse("2013-11-11")  => #<Date: 2013-11-11 ...>

 > Date.parse("11/11/2013")  => #<Date: 2013-11-11 ...>

 > Date.parse("11-11-13")
  => #<Date: 2011-11-13 ((2455818j,0s,0n),+0s,2299161j)>  # OOPS!

Strptime



 > Date.strptime("2013-11-11", "%Y-%m-%d")    => #<Date: 2013-11-11 ... >

 > Date.strptime("11/11/2013", "%m/%d/%Y")    => #<Date: 2013-11-11 ... >

 > Date.strptime("11-11-13", "%m-%d-%y")  => #<Date: 2013-11-11 ... >

Rails Date/Time


 $ rails c
 > Date.new
  => Mon, 01 Jan -4712
 > Time.new
  => 2013-11-10 21:02:13 -0600
 > DateTime.new
  => Mon, 01 Jan -4712 00:00:00 +0000




What's up with that?

ActiveSupport


Provides Ruby language extensions and utilities.


http://guides.rubyonrails.org/active_support_core_extensions.html


https://github.com/rails/rails/tree/master/activesupport/lib/active_support/core_ext

Displaying Dates/Times


 # open_camp/app/views/tasks/_task.html.erb
  <div class="span2">
    <%= task.due_date %>
  </div>

Displaying Dates/Times


Change Date Format


  # open_camp/app/views/tasks/_task.html.erb  <div class="span2">
    <%= task.due_date.strftime("%b %d, %Y") %>  </div>

Change Date Format



Define Custom Format

via Localization

 # config/locales/en.yml
en:
  hello: "Hello world"
  date:
    formats:
      awesometown: "%b %d, %y"
 # app/views/tasks/_task.html.erb
  <div class="span2">
    <%= l task.due_date, :format => :awesometown %>
  </div>

Define Custom Format



Define Custom Format

via Initializer

 2.0.0p247 :025 > Date::DATE_FORMATS
 => {:short=>"%e %b", :long=>"%B %e, %Y", :db=>"%Y-%m-%d", :number=>"%Y%m%d", :long_ordinal=>#<Proc:0x007f8d7aa31100@/Users/nick/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-3.2.13/lib/active_support/core_ext/date/conversions.rb:12 (lambda)>, :rfc822=>"%e %b %Y"}
 # config/initializers/date_formats.rb
   Date::DATE_FORMATS[:awesometown] = "%b %d, %y"



 # app/views/tasks/_task.html.erb
  <div class="span2">
    <%= task.due_date.to_s(:awesometown) %>
  </div>

Set as Default


 # config/initializers/date_formats.rb Date::DATE_FORMATS[:default] = "%b %d, %y"

 # app/views/tasks/_task.html.erb  <div class="span2">
    <%= task.due_date %>
  </div>

Extensions to Date/DateTime


yesterday
tomorrow
beginning_of_week (at_beginning_of_week)
end_of_week (at_end_of_week)
monday
sunday
weeks_ago
prev_week (last_week)
next_week
months_ago
months_since
beginning_of_month (at_beginning_of_month)
end_of_month (at_end_of_month)
prev_month (last_month)
next_month
beginning_of_quarter (at_beginning_of_quarter)
end_of_quarter (at_end_of_quarter)
beginning_of_year (at_beginning_of_year)
end_of_year (at_end_of_year)
years_ago
years_since
prev_year (last_year)
next_year



 $ irb
 > Date.today.tomorrow
  => NoMethodError: undefined method `tomorrow' for #<Date: 2013-11-11 ...
 > Date.today.next_week  => NoMethodError: undefined method `next_week' for #<Date: 2013-11-11 ...
 > Date.today.beginning_of_year  => NoMethodError: undefined method `beginning_of_year' for #<Date: 2013-11-11 ...



 $ rails c
 > Date.today.tomorrow
  => Tue, 12 Nov 2013

 > Date.today.next_week
  => Mon, 18 Nov 2013

 > Date.today.beginning_of_year
  => Tue, 01 Jan 2013

Open Camp Exercise




Add the ability to repeat a task daily, weekly, monthly until a specified date.  

Use ActiveSupport extensions to make your life easier and code easier to understand.

Working with Dates in Rails

By Nick Nguyen

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Working with Dates in Rails

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