How to populate owner name instead of id from a child object

Question

Here i am trying to get owner name value from child object incident , OwnerId is populating correctly but when i tried with Owner.Name, value is coming null in debug log.

Please find my piece of code below and suggest me how to get incident Owner Name in case record Incident_Owner__c field.(Parent : case Child : Incident)

trigger Updateincident on BMCServiceDesk__Incident__c (after insert, after update) 
{ 
  //You want it on update too, right?
  Map<ID, Case> parentCases = new Map<ID, Case>(); //Making it a map instead of list for easier lookup
  List<Id> listIds = new List<Id>();

  for (BMCServiceDesk__Incident__c childObj : Trigger.new) {
       listIds.add(childObj.Cases__c);
       System.debug('@@@@@@@@@@@@'+listIds);
  }

  parentCases = new Map<Id, Case>([SELECT id,Helpdesk_Case_Status__c,Helpdesk_Case_Resolution__c,(SELECT ID,Name, BMCServiceDesk__FKStatus__c,Owner.Name,BMCServiceDesk__Status_ID__c,BMCServiceDesk__incidentResolution__c FROM Incidents__r) FROM Case WHERE ID IN :listIds]);
      System.debug('@@@@@@@@@@@@'+parentCases );

  for(BMCServiceDesk__Incident__c inc: Trigger.new){
       Case myParentCse = parentCases .get(inc.Cases__c);
       myParentCse.Helpdesk_Case_Resolution__c = inc.BMCServiceDesk__incidentResolution__c;
       myParentCse.Helpdesk_Case_Status__c = inc.BMCServiceDesk__Status_ID__c;
       myParentCse.Incident_Owner__c = inc.Owner.Name;
        System.debug('@@@@@@@@@@@@'+myParentCse.Incident_Owner__c);
       myParentCse.Incident_Number__c = inc.Name;

       System.debug('@@@@@@@@@@@@'+myParentCse.Helpdesk_Case_Resolution__c);
  }
     update parentCases.values();
     System.debug('@@@@@@@@@@@@'+parentCases.values());
}

Answer 1

This is one of those questions I would want to debug out myself and test a little bit but I believe you can do this, you have the Incidents in your parent case map, so if you loop through your incidents__r that are inside your parent cases you have access to Owner.Name. So battery.cords answer is helpful I believe you could do it this way also

trigger Updateincident on BMCServiceDesk__Incident__c (after insert, after update) 
{ 
    Map<ID, Case> parentCases = new Map<ID, Case>(); //Making it a map instead of list for easier lookup
    Set<ID> bmsdID = new Set<ID>();

    for(BMCServiceDesk__Incident__c childObj : Trigger.new) 
    {
        bmsdID.add(childObj.Cases__c);
    }

    parentCases = new Map<Id, Case>([SELECT id,Helpdesk_Case_Status__c,Helpdesk_Case_Resolution__c,
        (SELECT ID,Name, BMCServiceDesk__FKStatus__c,Owner.Name,BMCServiceDesk__Status_ID__c,BMCServiceDesk__incidentResolution__c FROM Incidents__r) FROM Case WHERE ID IN :bmsdID]);

    for(ID caseID : parentCases.keySet())
    {
        for(Incidents__r incidents : parentCases.get(caseID).Incidents__r)
        {
            parentCases.get(caseID).Helpdesk_Case_Resolution__c = incidents.BMCServiceDesk__incidentResolution__c;
            parentCases.get(caseID).Helpdesk_Case_Resolution__c = incidents.BMCServiceDesk__incidentResolution__c;
            parentCases.get(caseID).Helpdesk_Case_Status__c = incidents.BMCServiceDesk__Status_ID__c;
            parentCases.get(caseID).Incident_Owner__c = incidents.Owner.Name;
            parentCases.get(caseID).Incident_Number__c = incidents.Name;
        }
    }

    update parentCases.values();
}

Answer 2

Related fields in trigger context are null unless queried explicitly. Your options are to either:

1. Query your users based on the values from OwnerId
2. Create a formula field Owner_Name__c, which returns the text of Owner.Name, allowing to you use the formula in your trigger.

I usually prefer a formula over the query, since its cheaper, and you can re-use it on search layouts or related lists.