# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 17
def beginning_of_week
  Thread.current[:beginning_of_week] || beginning_of_week_default || :monday
end

Returns the week start (e.g. :monday) for the current request, if this has been set (via ::beginning_of_week=). If Date.beginning_of_week has not been set for the current request, returns the week start specified in config.beginning_of_week. If no config.beginning_of_week was specified, returns :monday.

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 25
def beginning_of_week=(week_start)
  Thread.current[:beginning_of_week] = find_beginning_of_week!(week_start)
end

Sets Date.beginning_of_week to a week start (e.g. :monday) for current request/thread.

This method accepts any of the following day symbols: :monday, :tuesday, :wednesday, :thursday, :friday, :saturday, :sunday

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 46
def current
  ::Time.zone ? ::Time.zone.today : ::Date.today
end

Returns Time.zone.today when Time.zone or config.time_zone are set, otherwise just returns Date.today.

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 30
def find_beginning_of_week!(week_start)
  raise ArgumentError, "Invalid beginning of week: #{week_start}" unless ::Date::DAYS_INTO_WEEK.key?(week_start)
  week_start
end

Returns week start day symbol (e.g. :monday), or raises an ArgumentError for invalid day symbol.

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 41
def tomorrow
  ::Date.current.tomorrow
end

Returns a new Date representing the date 1 day after today (i.e. tomorrow's date).

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 36
def yesterday
  ::Date.current.yesterday
end

Returns a new Date representing the date 1 day ago (i.e. yesterday's date).

# File activesupport/lib/active_support/core_ext/date/acts_like.rb, line 5
def acts_like_date?
  true
end

Duck-types as a Date-like class. See Object#acts_like?.

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 110
def advance(options)
  options = options.dup
  d = self
  d = d >> options.delete(:years) * 12 if options[:years]
  d = d >> options.delete(:months)     if options[:months]
  d = d +  options.delete(:weeks) * 7  if options[:weeks]
  d = d +  options.delete(:days)       if options[:days]
  d
end

Provides precise Date calculations for years, months, and days. The options parameter takes a hash with any of these keys: :years, :months, :weeks, :days.

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 53
def ago(seconds)
  in_time_zone.since(-seconds)
end

Converts Date to a Time (or DateTime if necessary) with the time portion set to the beginning of the day (0:00) and then subtracts the specified number of seconds.

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 65
def beginning_of_day
  in_time_zone
end

Converts Date to a Time (or DateTime if necessary) with the time portion set to the beginning of the day (0:00)

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 125
def change(options)
  ::Date.new(
    options.fetch(:year, year),
    options.fetch(:month, month),
    options.fetch(:day, day)
  )
end

Returns a new Date where one or more of the elements have been changed according to the options parameter. The options parameter is a hash with a combination of these keys: :year, :month, :day.

Date.new(2007, 5, 12).change(day: 1)               # => Date.new(2007, 5, 1)
Date.new(2007, 5, 12).change(year: 2005, month: 1) # => Date.new(2005, 1, 12)

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 134
def compare_with_coercion(other)
  if other.is_a?(Time)
    to_datetime <=> other
  else
    compare_without_coercion(other)
  end
end

Allow Date to be compared with Time by converting to DateTime and relying on the <=> from there.

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 83
def end_of_day
  in_time_zone.end_of_day
end

Converts Date to a Time (or DateTime if necessary) with the time portion set to the end of the day (23:59:59)

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 73
def middle_of_day
  in_time_zone.middle_of_day
end

Converts Date to a Time (or DateTime if necessary) with the time portion set to the middle of the day (12:00)

# File activesupport/lib/active_support/core_ext/date/conversions.rb, line 67
def readable_inspect
  strftime("%a, %d %b %Y")
end

Overrides the default inspect method with a human readable one, e.g., “Mon, 21 Feb 2005”

# File activesupport/lib/active_support/core_ext/date/calculations.rb, line 59
def since(seconds)
  in_time_zone.since(seconds)
end

Converts Date to a Time (or DateTime if necessary) with the time portion set to the beginning of the day (0:00) and then adds the specified number of seconds

# File activesupport/lib/active_support/core_ext/date/conversions.rb, line 52
def to_formatted_s(format = :default)
  if formatter = DATE_FORMATS[format]
    if formatter.respond_to?(:call)
      formatter.call(self).to_s
    else
      strftime(formatter)
    end
  else
    to_default_s
  end
end

Convert to a formatted string. See DATE_FORMATS for predefined formats.

This method is aliased to to_s.

date = Date.new(2007, 11, 10)       # => Sat, 10 Nov 2007

date.to_formatted_s(:db)            # => "2007-11-10"
date.to_s(:db)                      # => "2007-11-10"

date.to_formatted_s(:short)         # => "10 Nov"
date.to_formatted_s(:number)        # => "20071110"
date.to_formatted_s(:long)          # => "November 10, 2007"
date.to_formatted_s(:long_ordinal)  # => "November 10th, 2007"
date.to_formatted_s(:rfc822)        # => "10 Nov 2007"
date.to_formatted_s(:iso8601)       # => "2007-11-10"

Adding your own date formats to #to_formatted_s

You can add your own formats to the Date::DATE_FORMATS hash. Use the format name as the hash key and either a strftime string or Proc instance that takes a date argument as the value.

# config/initializers/date_formats.rb
Date::DATE_FORMATS[:month_and_year] = '%B %Y'
Date::DATE_FORMATS[:short_ordinal] = ->(date) { date.strftime("%B #{date.day.ordinalize}") }

# File activesupport/lib/active_support/core_ext/date/conversions.rb, line 82
def to_time(form = :local)
  raise ArgumentError, "Expected :local or :utc, got #{form.inspect}." unless [:local, :utc].include?(form)
  ::Time.send(form, year, month, day)
end

Converts a Date instance to a Time, where the time is set to the beginning of the day. The timezone can be either :local or :utc (default :local).

date = Date.new(2007, 11, 10)  # => Sat, 10 Nov 2007

date.to_time                   # => 2007-11-10 00:00:00 0800
date.to_time(:local)           # => 2007-11-10 00:00:00 0800

date.to_time(:utc)             # => 2007-11-10 00:00:00 UTC

# File activesupport/lib/active_support/core_ext/date/conversions.rb, line 92
def xmlschema
  in_time_zone.xmlschema
end

Returns a string which represents the time in used time zone as DateTime defined by XML Schema:

date = Date.new(2015, 05, 23)  # => Sat, 23 May 2015
date.xmlschema                 # => "2015-05-23T00:00:00+04:00"