Hi and good day!
Its my first time here, and sorry for my bad english or grammar haha.
So, I decided to post this thing here,as my first post.
Recently theres a bug in my company website, where holiday event in calendar not showing some event, which is Hanukkah. AFter searching and debugging, the cause is actually just no new date set for Hanukkah in calendar again starts 2023 in database lol. So, I need to re-add back Hanukkah date in every year to database. But wait, the problem is I need to found out when Hanukkah is happened every year so I can generated it and store in database. The problem is Hanukkah is a Jewish event which occurance based on Jewish calendar, Hebrew calendar. So, in our standard calendar, Gregorian calendar (Jan,Feb,March,etc..) will have different date every year to celebrate the Hanukkah. Hanukkah is in 25 Kieslev every year in Hebrew Calendar or I can say
25 Kieslev 5783 is equal to 7 December 2023 in our date.
How to get the every year date for Hanukkah? I need to convert every year date start 5783 to 5816 (2023 to 2055) and store it in my database :-).
So, the main function need is actually convert hebrew date to gregorian date.
After searching the web for solution, I had found one library(gem) for Ruby on Rails to convert it. But nahh, feel lazy to installed it for just one used. So I finally some found post, from dafaweek;
http://www.dafaweek.com/HebCal/HebCalSampleSource.php that shows code to convert hebrew to gregorian date, but its in Javascript. So, I come out to try to convert it in Ruby lang then. After few ours of changing and testing code, result as below
Below is a Ruby on Rails functions of hebrew to gregorian date I translated from dafaweek.com where its originated language is in Javascript.
# --------------------------------------------------------------- all function needed to convert start
def MonSinceFirstMolad(nYearH)
#below formula is shortcut or
# (((235 * nYearH) - 234) / 19).floor(0)
# // A shortcut to this function can simply be the following formula
# // return Math.floor(((235 * nYearH) - 234) / 19)
# // This formula is found in Remy Landau's website and he
# // attributes it to Wolfgang Alexander Shochen. I will use a less
# // optimized function which I believe shows the underlying logic better.
# // count how many months there has been in all years up to last
# // year. The months of this year hasn't happened yet.
nYearH --
# // In the 19 year cycle, there will always be 235 months. That
# // would be 19 years times 12 months plus 7 extra month for the
# // leap years. (19 * 12) + 7 = 235.
# // Get how many 19 year cycles there has been and multiply it by 235
nMonSinceFirstMolad = (nYearH / 19).floor(0) * 235
# // Get the remaining years after the last complete 19 year cycle
nYearH = nYearH % 19
# // Add 12 months for each of those years
nMonSinceFirstMolad += 12 * nYearH
# // Add the extra months to account for the leap years
if (nYearH >= 17)
nMonSinceFirstMolad += 6
elsif (nYearH >= 14)
nMonSinceFirstMolad += 5
elsif (nYearH >= 11)
nMonSinceFirstMolad += 4
elsif (nYearH >= 8)
nMonSinceFirstMolad += 3
elsif (nYearH >= 6)
nMonSinceFirstMolad += 2
elsif (nYearH >= 3)
nMonSinceFirstMolad += 1
end
return nMonSinceFirstMolad
end
def IsLeapYear(nYearH)
nYearInCycle = nYearH % 19
( nYearInCycle == 3 ||
nYearInCycle == 6 ||
nYearInCycle == 8 ||
nYearInCycle == 11 ||
nYearInCycle == 14 ||
nYearInCycle == 17 ||
nYearInCycle == 0)
end
def Tishrei1(nYearH)
nMonthsSinceFirstMolad = MonSinceFirstMolad(nYearH)
nChalakim = 793 * nMonthsSinceFirstMolad
nChalakim += 204
nHours = (nChalakim / 1080).floor(0)
nChalakim = nChalakim % 1080
nHours += nMonthsSinceFirstMolad * 12
nHours += 5
# // carry the excess hours over to the days
nDays = (nHours / 24).floor(0)
nHours = nHours % 24
nDays += 29 * nMonthsSinceFirstMolad
nDays += 2
# // figure out which day of the week the molad occurs.
# // Sunday = 1, Moday = 2 ..., Shabbos = 0
nDayOfWeek = nDays % 7
# // In a perfect world, Rosh Hashanah would be on the day of the
# // molad. The Hebrew calendar makes four exceptions where we
# // push off Rosh Hashanah one or two days. This is done to
# // prevent three situation. Without explaining why, the three
# // situations are:
# // 1) We don't want Rosh Hashanah to come out on Sunday,
# // Wednesday or Friday
# // 2) We don't want Rosh Hashanah to be on the day of the
# // molad if the molad occurs after the beginning of 18th
# // hour.
# // 3) We want to limit years to specific lengths. For non-leap
# // years, we limit it to either 353, 354 or 355 days. For
# // leap years, we limit it to either 383, 384 or 385 days.
# // If setting Rosh Hashanah to the day of the molad will
# // cause this year, or the previous year to fall outside
# // these lengths, we push off Rosh Hashanah to get the year
# // back to a valid length.
# // This code handles these exceptions.
if(!IsLeapYear(nYearH) && nDayOfWeek == 3 && (nHours * 1080) + nChalakim >= (9 * 1080) + 204)
# // This prevents the year from being 356 days. We have to push
# // Rosh Hashanah off two days because if we pushed it off only
# // one day, Rosh Hashanah would comes out on a Wednesday. Check
# // the Hebrew year 5745 for an example.
nDayOfWeek = 5
nDays += 2
elsif( IsLeapYear(nYearH - 1) && nDayOfWeek == 2 && (nHours * 1080) + nChalakim >= (15 * 1080) + 589 )
# // This prevents the previous year from being 382 days. Check
# // the Hebrew Year 5766 for an example. If Rosh Hashanah was not
# // pushed off a day then 5765 would be 382 days
nDayOfWeek = 3
nDays += 1
else
# // see rule 2 above. Check the Hebrew year 5765 for an example
if (nHours >= 18)
nDayOfWeek += 1
nDayOfWeek = nDayOfWeek % 7
nDays += 1
end
# // see rule 1 above. Check the Hebrew year 5765 for an example
if (nDayOfWeek == 1 || nDayOfWeek == 4 ||nDayOfWeek == 6)
nDayOfWeek += 1
nDayOfWeek = nDayOfWeek % 7
nDays += 1
end
end
# // Here we want to add nDays to creation dTishrie1 = creation + nDays
# // Unfortunately, Many languages do not handle negative years very
# // well. I therefore picked a Random date (1/1/1900) and figured out
# // how many days it is after the creation (2067025). Then I
# // subtracted 2067025 from nDays.
nDays -= 2067025
dTishrei1 = Date.new(1900,1,1) #// 2067025 days after creation
dTishrei1 = (dTishrei1 + nDays.days)
return dTishrei1
end
def LengthOfYear(nYearH)
# // subtract the date of this year from the date of next year
dThisTishrei1 = Tishrei1(nYearH)
dNextTishrei1 = Tishrei1(nYearH + 1)
# // Java's dates are stored in milliseconds. To convert it into days
# // we have to divide it by 1000 * 60 * 60 * 24 if ruby no need
diff = (dNextTishrei1 - dThisTishrei1) #/( 1000 * 60 * 60 * 24)
return (diff).round()
end
def HebToGreg(nYearH, nMonthH, nDateH)
bLeap = IsLeapYear(nYearH)
nLengthOfYear = LengthOfYear(nYearH)
# // The regular length of a non-leap year is 354 days.
# // The regular length of a leap year is 384 days.
# // On regular years, the length of the months are as follows
# // Tishrei (1) 30
# // Cheshvan(2) 29
# // Kislev (3) 30
# // Teves (4) 29
# // Shevat (5) 30
# // Adar A (6) 30 (only valid on leap years)
# // Adar (7) 29 (Adar B for leap years)
# // Nisan (8) 30
# // Iyar (9) 29
# // Sivan (10) 30
# // Tamuz (11) 29
# // Av (12) 30
# // Elul (13) 29
# // If the year is shorter by one less day, it is called a haser
# // year. Kislev on a haser year has 29 days. If the year is longer
# // by one day, it is called a shalem year. Cheshvan on a shalem year is 30 days.
bHaser = (nLengthOfYear == 353 || nLengthOfYear == 383)
bShalem = (nLengthOfYear == 355 || nLengthOfYear == 385)
# // get the date for Tishrei 1
dGreg = Tishrei1(nYearH)
# // Now count up days within the year
for nMonth in 1..(nMonthH-1) do
if (nMonth == 1 ||
nMonth == 5 ||
nMonth == 8 ||
nMonth == 10 ||
nMonth == 12 )
nMonthLen = 30
elsif (nMonth == 4 ||
nMonth == 7 ||
nMonth == 9 ||
nMonth == 11 ||
nMonth == 13 )
nMonthLen = 29
elsif (nMonth == 6)
nMonthLen = (bLeap ? 30 : 0)
elsif (nMonth == 2)
nMonthLen = (bShalem ? 30 : 29)
elsif (nMonth == 3)
nMonthLen = (bHaser ? 29 : 30 )
end
dGreg = dGreg + nMonthLen.days
end
dGreg = dGreg + nDateH.days - 1 - 1
return dGreg
end
# --------------------------------------------------------------- end all function needed
So, in ruby on rails .rb if you want to convert hebrew date and use above function just call HebToGreg(yearparam,monthparam,dayparam) as i.e. below:
(HebToGreg(5783,3,25));
(HebToGreg(5784,3,25));
(HebToGreg(5785,3,25));
(HebToGreg(5786,3,25));
(HebToGreg(5787,3,25));
(HebToGreg(5788,3,25));
(HebToGreg(5789,3,25));
(HebToGreg(5790,3,25));
So,there it is. I just put all the function needed in my module and call it when need. Now I can generate Hanukkah date in Gregorian calendar and seed it to save in my database.
Thanks for read this guys, terima kasih.
