add primary contact to opportunity

gistfile1.txt

trigger AddPrimaryContactToOpp on Opportunity (before insert, before update) {
// THIS TRIGGER WILL OVERWRITE ANY CONTACT DEFINED IN THE CUSTOM FIELD CONTACT__C ON THE OPPORTUNITY OBJECT.
// SET THIS FIELD TO READ ONLY OR CHANGE THE FUNCTIONALITY BELOW TO AVIOD DATA BEEING OVERWRITTEN BY MISTAKE...

   for (Opportunity o : Trigger.new) {
   // o.NextStep = 'DEBUG: Running function...';

 


       // CREATE ARRAY OF ALL CONTACT ROLES ON THIS OPPORTUNITY. THE REASON WHY WE DONT PICK THE PRIMARY CONTACT ROLE ONLY
       // IS BECAUSE THE PRIMARY FLAG IS NOT SET WHEN LEADS ARE CONVERTED TO OPPORTUNITIES. ONLY WHEN CREATING OPPORTUNITIES
       // MANUALLY FROM THE CONTACT OBJECT THE IS PRIMARY CHECKBOX IS CHECKED...


       OpportunityContactRole[] contactRoleArray =
       [select ContactID, isPrimary from OpportunityContactRole where OpportunityId = :o.id ORDER BY isPrimary DESC, createdDate];
       if (contactRoleArray.size() > 0) {
         
           // IF PRIMARY IS DEFINED THEN THIS WILL BE THE FIRST OBJECT. IF NOT THE FIRST ADDED CONTACT ROLE WILL BE ADDED...
           o.Contact__c = contactRoleArray[0].ContactID;
          
       }else{
      
           // IF NO CONTACT ROLES EXIST RETURN NULL...
           o.Contact__c = null;
           // o.NextStep = 'DEBUG; CONTACT = null ';
       }
   }
 }