Hi all,

How to Write DML Statements in try catch block 

// Handler Class
 
public class CountContactHandler
{
                public static void countContacts(List<Contact> conList){
                                Set<Id> setAccountIds = new Set<Id>();
                                for(Contact con : conList)
                                {
                                                setAccountIds.add(con.AccountId);
                                }
                               
                                List<Account> listAccs = [Select id,name,Total_No_Of_Contacts__c ,(Select id,Contact_Roll__c from contacts) from Account where Id in : setAccountIds];
                               
                                for(Account acc :listAccs)
                                {
                                                Integer i=0,j = 0;
                                                for(Contact conItr : acc.Contacts){
                                                                if(conItr.Contact_Roll__c)
                {
                    i++;
                }
                                                                j++;
                                               
                                                }
                                                acc.No_of_active_contacts__c = i;
                                                acc.Total_No_Of_Contacts__c = j;
                                }
                                update listAccs;
                }
}
// Trigger
 
trigger countContact on Contact (after insert, after update, after delete, after undelete)
{
                Set<Id> setAccountIds = new Set<Id>();
 
                //Whenever your working with After Undelete operation you can access data through
                //Trigger.new or Trigger.newMap but not with Trigger.old or Trigger.oldmap variables
                if(Trigger.isInsert || Trigger.isUndelete || Trigger.isUpdate)
                {
                                CountContactHandler.countContacts(Trigger.new);
                }
 
                else if(Trigger.isDelete)
                {
                                //if you use Trigger.new below in place of Trigger.old you will end up with
                                //System.NullPointerException:Attempt to de-reference a null object
                                CountContactHandler.countContacts(Trigger.old);
                }
}

Kindly support and suggest

Thanks