SObject row does not allow errors

Question

If I use adderror as below I get the following error. How do I fix it?

SObject row does not allow errors

trigger LocationJunctionTrigger on Location_Junction__c (After insert,After Update)
{
    set<id> locid =new set<id>();
    set<id> junid =new set<id>();
    for(Location_Junction__c jun:trigger.new){

        locid.add(jun.location__c);
        junid.add(jun.id);
    }
    if(trigger.isAfter && (trigger.isInsert || trigger.isUpdate))
    {
        list<Location_Junction__c> currentList = [SELECT Id,Location__c,Opportunity__r.Start_Date__c,Opportunity__r.AccountId from Location_Junction__c WHERE Location__c IN :locid AND Id IN : junid];
        list<Location_Junction__c> existingList = [SELECT Id,Location__c,Opportunity__r.Start_Date__c,Opportunity__r.closedate,Opportunity__r.AccountId from Location_Junction__c WHERE Location__c IN :locid AND Id Not IN : junid];

        for(Location_Junction__c currentLocation :currentList)
        {
            for(Location_Junction__c existingLocation :existingList){
    if( existingLocation.Opportunity__r.AccountId == currentLocation.Opportunity__r.AccountId && currentLocation.Opportunity__r.Start_Date__c < existingLocation.Opportunity__r.closedate && currentLocation.Opportunity__r.Start_Date__c > existingLocation.Opportunity__r.Start_Date__c)

              currentLocation.Location__c.adderror('Please select different location');
                }
        }
    }
}

Answer 1

This is the solution for the above post

Map<id,Location_junction__C> Mapjun = Trigger.newmap;
Mapjun.get(currentLocation.id).Location__c.adderror('Please select different location');

Answer 2

.addError can be called on Trigger.new in before/after insert and before/after update triggers, and on Trigger.old in before delete List. You can't add this to any other sObject that is why error is saying SObject row does not allow error.

So in your case you can add this to Location_Junction__c

Answer 3

You can use the addError method for only those records that are avaliable in Trigger Context. You are calling the addError on a field instead of sObject. Change the line to

provided currentLocation is part of the trigger context

 currentLocation.adderror('Please select different location');

You are traversing through existingList and you have populated with non trigger context records.

for(Location_Junction__c jun:trigger.new){

        locid.add(jun.location__c);
        junid.add(jun.id);
    }

    list<Location_Junction__c> existingList = [SELECT Id,Location__c,Opportunity__r.Start_Date__c,Opportunity__r.closedate,Opportunity__r.AccountId from Location_Junction__c WHERE Location__c IN :locid AND Id Not IN : junid];

What is the business logic here ? You want to throw errors for records which are not in trigger context ?