Ruby On Rails in UA/Code Review, теоретические вопросы/Работа с датами date_cheat_sheet

Введение
Time.now # => Sat Mar 18 14:49:30 EST 2006 Time.at(0) # => Wed Dec 31 19:00:00 EST 1969 #--- t = Time.at(0) t.sec # => 0 t.min # => 0 t.hour # => 19 t.day # => 31 t.month # => 12 t.year # => 1969 t.wday # => 3 # Numeric day of week; Sunday is 0 t.yday # => 365 # Numeric day of year t.isdst # => false # Is Daylight Saving Time in effect? t.zone # => "EST" # Time zone #--- Time.local(1865, 4, 9) # ArgumentError: time out of range Time.local(2100, 1, 1) # ArgumentError: time out of range #--- require 'date' DateTime::new(1865, 4, 9).to_s # => "1865-04-09T00:00:00Z" DateTime::new(2100, 1, 1).to_s # => "2100-01-01T00:00:00Z" #--- # Time zero for the date library: DateTime::new.to_s # => "-4712-01-01T00:00:00Z" # The current date and time: DateTime::now.to_s # => "2006-03-18T14:53:18-0500" #--- Time.local(1865,4,9) # => Sun Apr 09 00:00:00 EWT 1865 Time.local(2100,1,1) # => Fri Jan 01 00:00:00 EST 2100 #---

Поиск сегодняшней даты а зависимотси от формата
now = Time.now # => Sat Mar 18 16:58:07 EST 2006 now.gmtime # => Sat Mar 18 21:58:07 UTC 2006 #The original object was affected by the time zone conversion. now # => Sat Mar 18 21:58:07 UTC 2006 #--- require 'date' now = DateTime.now # => #<DateTime: 70669826362347677/28800000000,-5/24,2299161> now.to_s # => "2006-03-18T16:58:07-0500" now.new_offset.to_s # => "2006-03-18T21:58:07Z" #The original object was not affected by the time zone conversion. now.to_s # => "2006-03-18T16:58:07-0500" #--- now_time = Time.new now_datetime = DateTime.now now_time.year # => 2006 now_datetime.year # => 2006 now_time.hour # => 18 now_datetime.hour # => 18 now_time.zone # => "EST" now_datetime.zone # => "-0500" now_time.isdst # => false #--- now_datetime.offset # => Rational(-5, 24) # -5 hours #--- now_time.usec # => 247930 # That is, 247930 microseconds now_datetime.sec_fraction # => Rational(62191, 21600000000) # That is, about 287921 microseconds #--- class Date def Date.now return Date.jd(DateTime.now.jd) end end puts Date.now # 2006-03-18 #--- Time.local(1999, 12, 31, 23, 21, 5, 1044) # => Fri Dec 31 23:21:05 EST 1999 Time.gm(1999, 12, 31, 23, 21, 5, 22, 1044) # => Fri Dec 31 23:21:05 UTC 1999 Time.local(1991, 10, 1) # => Tue Oct 01 00:00:00 EDT 1991 Time.gm(2000) # => Sat Jan 01 00:00:00 UTC 2000 #--- DateTime.civil(1999, 12, 31, 23, 21, Rational(51044, 100000)).to_s # => "1999-12-31T23:21:00Z" DateTime.civil(1991, 10, 1).to_s # => "1991-10-01T00:00:00Z" DateTime.civil(2000).to_s # => "2000-01-01T00:00:00Z" #--- my_offset = DateTime.now.offset # => Rational(-5, 24) DateTime.civil(1999, 12, 31, 23, 21, Rational(51044, 100000), my_offset).to_s # => "1999-12-31T23:21:00-0500" #--- #In Italy, 4 Oct 1582 was immediately followed by 15 Oct 1582. # Date.new(1582, 10, 4).to_s # => "1582-10-04" Date.new(1582, 10, 5).to_s # ArgumentError: invalid date Date.new(1582, 10, 4).succ.to_s # => "1582-10-15" #In England, 2 Sep 1752 was immediately followed by 14 Sep 1752. # Date.new(1752, 9, 2, Date::ENGLAND).to_s # => "1752-09-02" Date.new(1752, 9, 3, Date::ENGLAND).to_s # ArgumentError: invalid date Date.new(1752, 9, 2, DateTime::ENGLAND).succ.to_s # => "1752-09-14" Date.new(1582, 10, 5, Date::ENGLAND).to_s # => "1582-10-05" #---

Разбор параметров
require 'date' Date.parse('2/9/2007').to_s # => "2007-02-09" DateTime.parse('02-09-2007 12:30:44 AM').to_s # => "2007-09-02T00:30:44Z" DateTime.parse('02-09-2007 12:30:44 PM EST').to_s # => "2007-09-02T12:30:44-0500" Date.parse('Wednesday, January 10, 2001').to_s # => "2001-01-10" #--- Date.parse('2/9/07').to_s # => "0007-02-09" #--- american_date = '%m/%d/%y' Date.strptime('2/9/07', american_date).to_s # => "2007-02-09" DateTime.strptime('2/9/05', american_date).to_s # => "2005-02-09T00:00:00Z" Date.strptime('2/9/68', american_date).to_s # => "2068-02-09" Date.strptime('2/9/69', american_date).to_s # => "1969-02-09" european_date = '%d/%m/%y' Date.strptime('2/9/07', european_date).to_s # => "2007-09-02" Date.strptime('02/09/68', european_date).to_s # => "2068-09-02" Date.strptime('2/9/69', european_date).to_s # => "1969-09-02" four_digit_year_date = '%m/%d/%Y' Date.strptime('2/9/2007', four_digit_year_date).to_s # => "2007-02-09" Date.strptime('02/09/1968', four_digit_year_date).to_s # => "1968-02-09" Date.strptime('2/9/69', four_digit_year_date).to_s # => "0069-02-09" date_and_time = '%m-%d-%Y %H:%M:%S %Z' DateTime.strptime('02-09-2007 12:30:44 EST', date_and_time).to_s # => "2007-02-09T12:30:44-0500" DateTime.strptime('02-09-2007 12:30:44 PST', date_and_time).to_s # => "2007-02-09T12:30:44-0800" DateTime.strptime('02-09-2007 12:30:44 GMT', date_and_time).to_s # => "2007-02-09T12:30:44Z" twelve_hour_clock_time = '%m-%d-%Y %I:%M:%S %p' DateTime.strptime('02-09-2007 12:30:44 AM', twelve_hour_clock_time).to_s # => "2007-02-09T00:30:44Z" DateTime.strptime('02-09-2007 12:30:44 PM', twelve_hour_clock_time).to_s # => "2007-02-09T12:30:44Z" word_date = '%A, %B %d, %Y' Date.strptime('Wednesday, January 10, 2001', word_date).to_s # => "2001-01-10" #--- Date.parse('1/10/07').to_s # => "0007-01-10" Date.parse('2007 1 10').to_s # ArgumentError: 3 elements of civil date are necessary TRY_FORMATS = ['%d/%m/%y', '%Y %m %d'] def try_to_parse(s) parsed = nil TRY_FORMATS.each do |format| begin parsed = strptime(s, format) break rescue ArgumentError end end return parsed end try_to_parse('1/10/07').to_s # => "2007-10-01" try_to_parse('2007 1 10').to_s # => "2007-01-10" #--- require 'time' mail_received = 'Tue, 1 Jul 2003 10:52:37 +0200' Time.rfc822(mail_received) # => Tue Jul 01 04:52:37 EDT 2003 #--- last_modified = 'Tue, 05 Sep 2006 16:05:51 GMT' Time.httpdate(last_modified) # => Tue Sep 05 12:05:51 EDT 2006 #--- timestamp = '2001-04-17T19:23:17.201Z' t = Time.iso8601(timestamp) # => Tue Apr 17 19:23:17 UTC 2001 t.sec # => 17 t.tv_usec # => 201000 #--- t = Time.at(1000000000) # => Sat Sep 08 21:46:40 EDT 2001 t.rfc822 # => "Sat, 08 Sep 2001 21:46:40 -0400" t.httpdate # => "Sun, 09 Sep 2001 01:46:40 GMT" t.iso8601 # => "2001-09-08T21:46:40-04:00" #---

require 'date' (Date.new(1776, 7, 2)..Date.new(1776, 7, 4)).each { |x| puts x } # 1776-07-02 # 1776-07-03 # 1776-07-04 span = DateTime.new(1776, 7, 2, 1, 30, 15)..DateTime.new(1776, 7, 4, 7, 0, 0) span.each { |x| puts x } # 1776-07-02T01:30:15Z # 1776-07-03T01:30:15Z # 1776-07-04T01:30:15Z (Time.at(100)..Time.at(102)).each { |x| puts x } # Wed Dec 31 19:01:40 EST 1969 # Wed Dec 31 19:01:41 EST 1969 # Wed Dec 31 19:01:42 EST 1969 #--- the_first = Date.new(2004, 1, 1) the_fifth = Date.new(2004, 1, 5) the_first.upto(the_fifth) { |x| puts x } # 2004-01-01 # 2004-01-02 # 2004-01-03 # 2004-01-04 # 2004-01-05 #--- class Time def step(other_time, increment) raise ArgumentError, "step can't be 0" if increment == 0 increasing = self < other_time if (increasing && increment < 0) || (!increasing && increment > 0) yield self return end d = self begin yield d d += increment end while (increasing ? d <= other_time : d >= other_time) end def upto(other_time) step(other_time, 1) { |x| yield x } end end the_first = Time.local(2004, 1, 1) the_second = Time.local(2004, 1, 2) the_first.step(the_second, 60 * 60 * 6) { |x| puts x } # Thu Jan 01 00:00:00 EST 2004 # Thu Jan 01 06:00:00 EST 2004 # Thu Jan 01 12:00:00 EST 2004 # Thu Jan 01 18:00:00 EST 2004 # Fri Jan 02 00:00:00 EST 2004 the_first.upto(the_first) { |x| puts x } # Thu Jan 01 00:00:00 EST 2004 #---

require 'date' y2k = Time.gm(2000, 1, 1) # => Sat Jan 01 00:00:00 UTC 2000 y2k + 1 # => Sat Jan 01 00:00:01 UTC 2000 y2k - 1 # => Fri Dec 31 23:59:59 UTC 1999 y2k + (60 * 60 * 24 * 365) # => Sun Dec 31 00:00:00 UTC 2000 y2k_dt = DateTime.new(2000, 1, 1) (y2k_dt + 1).to_s # => "2000-01-02T00:00:00Z" (y2k_dt - 1).to_s # => "1999-12-31T00:00:00Z" (y2k_dt + 0.5).to_s # => "2000-01-01T12:00:00Z" (y2k_dt + 365).to_s # => "2000-12-31T00:00:00Z" #--- day_one = Time.gm(1999, 12, 31) day_two = Time.gm(2000, 1, 1) day_two - day_one # => 86400.0 day_one - day_two # => -86400.0 day_one = DateTime.new(1999, 12, 31) day_two = DateTime.new(2000, 1, 1) day_two - day_one # => Rational(1, 1) day_one - day_two # => Rational(-1, 1) # Compare times from now and 10 seconds in the future. before_time = Time.now before_datetime = DateTime.now sleep(10) Time.now - before_time # => 10.003414 DateTime.now - before_datetime # => Rational(5001557, 43200000000) #--- require 'rubygems' require 'active_support' 10.days.ago # => Wed Mar 08 19:54:17 EST 2006 1.month.from_now # => Mon Apr 17 20:54:17 EDT 2006 2.weeks.since(Time.local(2006, 1, 1)) # => Sun Jan 15 00:00:00 EST 2006 y2k - 1.day # => Fri Dec 31 00:00:00 UTC 1999 y2k + 6.3.years # => Thu Apr 20 01:48:00 UTC 2006 6.3.years.since y2k # => Thu Apr 20 01:48:00 UTC 2006 #--- (y2k_dt >> 1).to_s # => "2000-02-01T00:00:00Z" (y2k_dt << 1).to_s # => "1999-12-01T00:00:00Z" #--- y2k + 1.month # => Mon Jan 31 00:00:00 UTC 2000 y2k - 1.month # => Thu Dec 02 00:00:00 UTC 1999 #--- # Thirty days hath September... halloween = Date.new(2000, 10, 31) (halloween << 1).to_s # => "2000-09-30" (halloween >> 1).to_s # => "2000-11-30" (halloween >> 2).to_s # => "2000-12-31" leap_year_day = Date.new(1996, 2, 29) (leap_year_day << 1).to_s # => "1996-01-29" (leap_year_day >> 1).to_s # => "1996-03-29" (leap_year_day >> 12).to_s # => "1997-02-28" (leap_year_day << 12 * 4).to_s # => "1992-02-29" #---

Решение для установки значений по умолчанию для полей выбора месяца и даты,
пришлось генерировать дату и передавать методу, так как по умолчанию список полей месяцев или годов генерируется для даты переданной в качестве параметра.
<% date = Date.new( params[:card].nil? ? Time.now.year : params[:card]['year'].to_i , params[:card].nil? ? Time.now.month : params[:card]['month'].to_i , 11)%> <%= select_month( date,{:prefix=>'card', :field_name=>'month'} )%> - <%= select_year( date,{:start_year => 2007, :end_year => 2020, :prefix=>'card', :field_name=>'year'} )%>

А можно ссылку на источник с подобными вещами?