Hi there,

I am hoping you can help I am new to writing Triggers and I could really do with a hand. I have created a custom object called Campaign Team Member (Campaign_Team_Member__c) with a Master detail to Campaigns (Campaign__c) and a Lookup to Users (User__c). I have also added a text field to Campaigns called CampaignTeamIDs (CampaignTeamIDs__c).

What I am trying to do is on insert or update on Campaign Team Member check the values of CampaginTeamIDs__c add the Id in User__c to CampaignTeam_IDs__c if they do not exist and return an error if they do. On delete of the Campaign_Team_Member__c record I want to find the Campaign and remove the User Id from the CampaignTeamIDs__c field.

I then have a formula field that returns a true checkbox if the CampaignTeamIDs__c field contains the current user id, then I can use a list view to return My Team's Campaigns.

This is my code at the moment but I am unsure how to do a check on duplicate values in the CampaignTeamIDs__c before Insert
 

trigger UpdateCampaignTeamMembers on Campaign_Team_Member__c (after insert, after update, after delete, after undelete) {
   
	//If the event is insert or undelete, this list takes New Values or else it takes old values
	List<Campaign_Team_Member__c> CampaignTeamList = (Trigger.isInsert|| Trigger.isUnDelete) ? Trigger.new : Trigger.old;

    //set of Campaign Id's - lists can contain dupilcates.
    set<id> CampaignTeamIds = new set<id>();

    //Loop through the Campaign Team Member object Records to store the Campaign Team Member Id values
    for (Campaign_Team_Member__c Cam_team : CampaignTeamList) {
    	CampaignTeamIds.add(Cam_team.Campaign__c);
    }

	List<Campaign> CampaignList = [select id, (select Campaign__c, User__c from Campaign_Team_Members__r)
								from Campaign where id in :CampaignTeamIds];


	for (Campaign Camp : CampaignList) {

		if(Camp.Campaign_Team_Members__r.size() > 0){
  			Camp.CampaignTeamIDs__c = '';

  			for(integer i=0;i < Camp.Campaign_Team_Members__r.size();i++){
   				Camp.CampaignTeamIDs__c += string.valueOf(Camp.Campaign_Team_Members__r[i].User__c)+ '; ';
  			}
		}else Camp.CampaignTeamIDs__c = null;
    }
	//update the Campaign List
	update CampaignList;
}