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Upton_XUpton_X 

Last Day of Month for DATETIME method

Hello - I have been able to find how to calculate the first day of the month with a DateTime method, however I am struggling with DateTime for last day of month and have not been able to find anything online.

I need datetime specifically because I can only query Case.CreatedDate with that datatype.

Line 8 Specifically 
trigger ScratchTrigger on Case (before insert) {
//Write a trigger that will prevent each user from creating more than 99 cases a month
    
    //Create values for this month
    Date dayToday = Date.Today();
    DateTime firstDayOfMonth = DateTime.newInstance(daytoday.toStartOfMonth().addMonths(-1), Time.newInstance(0,0,0,0));
    
    DateTime lastDayOfMonth  = DateTime.newInstance(dayToday.addMonths(1).toStartofMonth().addDays(-1)), Time.newInstance(0,0,0,0));
        
    
    system.debug('Todays Date = '+dayToday+ ' firstDayOfMonth = '+firstDayOfMonth+ ' lastday of Month = '+lastDayOfMonth);
    
    //When a new case is crated, iterate through Trigger.New and add case to UserCreated Cases
    if(Trigger.isInsert){
    List<Case> UserCreatedCases = [SELECT Id, CreatedById, CreatedDate FROM Case WHERE (CreatedDated >= :firstDayOfMonth) AND (CreatedDate <= :lastDayOfMonth)];
    }
    
}

 
Malika Pathak 9Malika Pathak 9
Hi Upton,

By Date Method: 
Date firstDayOfMonth = System.today().toStartOfMonth();
To get the last day of the month: 
Date lastDayOfMonth = firstDayOfMonth.addDays(Date.daysInMonth(firstDayOfMonth.year(), firstDayOfMonth.month()) - 1);
The output would be: 
11:00:44:005 USER_DEBUG [5]|DEBUG|firstDayOfMonth 2021-02-01 00:00:00 11:00:44:005 USER_DEBUG [6]|DEBUG|lastDayOfMonth 2021-02-28 00:00:00

By DateTime Method: 
Integer month = 2;
Integer day = null;
Integer year = 2021;

// Create a new DateTime object for the first day of the month following
// the date you're looking for.
DateTime dtTarget = DateTime.newInstance(year, month, 1);
//In this case we would be sure that month would not be out of bound
dtTarget = dtTarget.addMonths(1);
// Then use the .addDays() method to add negative 1 days. This gives you
// the last day of the target month.
DateTime lastDayOfMonth = dtTarget.addDays(-1);
day = lastDayOfMonth.day();

System.debug(lastDayOfMonth);
System.debug(day);
The output would be; 
11:00:44:005 USER_DEBUG [15]|DEBUG|2021-02-28 11:00:00
11:00:44:005 USER_DEBUG [16]|DEBUG|28
you can modify this as per your requirements.

If you found this answer helpful mark this as best answers to help others.
Upton_XUpton_X

Hi Malika-

Thanks for the suggestion.  I am having a hard time with the origional value for dt taget which needs to be today() or Now() for date time.

 

Here is what I have that is producing an unexpcted outcome

 

DateTime dtTarget = DateTime.now();
system.debug('dtTarget = '+dtTarget);
dtTarget = dtTarget.addMonths(1);
system.debug('dtTarget with 1 month' + dtTarget);
DateTime lastDayofMonth = dtTarget.addDays(-1);
system.debug('lastDayofMonth = '+lastDayofMonth);
  
09:27:25:003 USER_DEBUG [6]|DEBUG|lastDayofMonth = 2021-03-12 16:27:25