DZone Snippets: date code

date_select conversion

indiehead (John) — Thu, 17 Apr 2008 13:20:35 GMT

function to convert a value from a date_select into a more sql-friendly value



<%=date_select(:date,'',:start_year => 1950,:include_blank => false, :default => { :year => '1970' })%>



def convert_date(obj) 

  return “#{obj[‘(1i)’]}-#{obj[‘(2i)’]}-#{obj[‘(3i)’]}” 

end

Convert Java date to GMT

frost137 (Douglas Wyatt) — Fri, 28 Mar 2008 20:56:15 GMT

This function converts a local date to GMT. This version corrects the bug common to this type of conversion where the date is incorrectly converted when the time is close to the DST crossover.



private static Date cvtToGmt( Date date )

{

   TimeZone tz = TimeZone.getDefault();

   Date ret = new Date( date.getTime() - tz.getRawOffset() );



   // if we are now in DST, back off by the delta.  Note that we are checking the GMT date, this is the KEY.

   if ( tz.inDaylightTime( ret ))

   {

      Date dstDate = new Date( ret.getTime() - tz.getDSTSavings() );



      // check to make sure we have not crossed back into standard time

      // this happens when we are on the cusp of DST (7pm the day before the change for PDT)

      if ( tz.inDaylightTime( dstDate ))

      {

         ret = dstDate;

      }

   }



   return ret;

}

Days since January 1st, 2008

mm53bar (Mike) — Sun, 23 Mar 2008 22:22:21 GMT

// I'm in a challenge to do one pushup and one crunch for each day of the new year. This little Ruby snippet will tell me how many I have to do!



(DateTime.now - DateTime.new(2008,1,1)).to_i

Rails Date Formats

willcodeforfoo () — Fri, 14 Mar 2008 14:32:10 GMT

// cribbed from http://wiki.rubyonrails.org/rails/pages/HowToDefineYourOwnDateFormat



my_formats = {

  :my_format_1 => '%l %p, %b %d, %Y',

  :my_format_2  => '%l:%M %p, %B %d, %Y'

}



ActiveSupport::CoreExtensions::Time::Conversions::DATE_FORMATS.merge!(my_formats)

ActiveSupport::CoreExtensions::Date::Conversions::DATE_FORMATS.merge!(my_formats)

Increment a date using Ruby

jrobertson (James Robertson) — Wed, 05 Mar 2008 13:43:34 GMT

This Ruby code converts a string into a date and increments the day, week, month, quarter or year.



def date_add(sdate='', unit='',i=0)



  sdate[/(\d+)\/(\d+)\/(\d+)\s(\d+):(\d+):(\d+)/]

  iyear = $3.to_i; imonth = $2.to_i; iday = $1.to_i; ihour = $4.to_i; imin = $5.to_i; isec = $6.to_i

  

  case  unit

    when 'days'

      t1 = Time.local(iyear,imonth,iday,ihour,imin,isec)

      t1 += (60 * 60 * 24 * i)

    when 'weeks'

      t1 = Time.local(iyear,imonth,iday,ihour,imin,isec)

      t1 += (60 * 60 * 24 * 7 * i) 

    when 'months'

      imonth += i

      if imonth < 12 then

        t1 = Time.local(iyear,imonth+i,iday,ihour,imin,isec)

      else

        t1 = Time.local(iyear+=1,imonth -12,iday,ihour,imin,isec)

      end

    when 'quarter'

      imonth += 3

      if imonth <= 12 then

        t1 = Time.local(iyear,imonth,iday,ihour,imin,isec)

      else

        t1 = Time.local(iyear+=1,imonth - 12,iday,ihour,imin,isec)

      end    

    when 'years'

      t1 = Time.local(iyear+i,imonth,iday,ihour,imin,isec)

    else

      raise 'not a valid date unit'

  end

  t1

end



date_add("17/03/2008 17:48:00",'months',2)

output: Sat May 17 17:48:00 +0100 2008

Creating a DateTime object with Ruby

jrobertson (James Robertson) — Sat, 01 Mar 2008 21:53:38 GMT

This example creates a date and time variable which represents 22nd March 2008 4:30pm and 12 seconds.



d2 = DateTime.new(y=200,m=3,d=22, h=16,min=30,s=12)

or convert a date string into a DataTime object:



"17/03/2009 17:48:00"[/(\d+)\/(\d+)\/(\d+)\s(\d+):(\d+):(\d+)/]

d2 = DateTime.new(y=$3.to_i,m=$2.to_i,d=$1.to_i, h=$4.to_i,min=$5.to_i,s=$6.to_i)

or convert a date string into a Time object:



"22/03/2008 17:48:00"[/(\d+)\/(\d+)\/(\d+)\s(\d+):(\d+):(\d+)/]

iyear = $3.to_i; imonth = $2.to_i; iday = $1.to_i; ihour = $4.to_i; imin = $5.to_i; isec = $6.to_i

twork = Time.local(iyear,imonth,iday,ihour,imin,isec) 

puts 'we still have time to party' if Time.now < twork

Reference:
Class: DateTime [ruby-doc.org]
Class: Time [ruby-doc.org]

Calculate last day of current Month

bmowbray (Brian Mowbray) — Wed, 27 Feb 2008 19:13:47 GMT

'Determines what the next month is based on today and subtracts 1 day from first day of next month.



'VB.NET

Dim NextMonth As Integer

Dim RptYear As Integer

'Determine next month

NextMonth = DatePart(DateInterval.Month, DateAdd(DateInterval.Month, +1, today))

'Determine the year of the next month, in case you are going from Dec to Jan

RptYear = DatePart(DateInterval.Year, DateAdd(DateInterval.Month, +1, today))

'Subtract 1 day from the first day of next month to get this months last day

Return DateAdd(DateInterval.Day, -1, DateValue(NextMonth.ToString & "/1/" & RptYear.ToString))

isWorkingDay?

caffo () — Wed, 13 Feb 2008 02:45:55 GMT

// description of your code here



  public boolean isWorkingDay(Date date) {

        Calendar cal = GregorianCalendar.getInstance();

        cal.setTime(date);

        int dayOfWeek = cal.get(Calendar.DAY_OF_WEEK); 

        if ((dayOfWeek  Calendar.SATURDAY) || (dayOfWeek  Calendar.SUNDAY)) {

            return false;

        } 

        return true;

   }

Calculate Last Day of Last Month

jokeyxero (xero) — Fri, 01 Feb 2008 22:51:12 GMT

VB/VBA/VB.NET one-liner to calculate the end of last month. Useful for SSRS/RDL Expressions and Excel/Office Formulas. Note that it does not use string parsing, which can cause localization problems.



DateAdd("d", -1.0 * DatePart("d", Today), Today)

Calculate First Day of Current Month

jokeyxero (xero) — Fri, 01 Feb 2008 22:48:45 GMT

VB/VBA/VB.NET one-liner to calculate the start of the current month. Useful for SSRS/RDL Expressions and Excel/Office Formulas. Note that it does not use string parsing, which can cause localization problems.



DateAdd("D", -1.0 * DatePart("D", Today) + 1, Today)