I have the following configuration:

I have a trigger in which I am trying to add an Inventory record when a treatment gets created. This inventory record requires an order ID as it has a master detail relationship to order. This treatment record has a lookup to the Visit Object which in turn has a lookup to a Work Order object which in turn has a lookup to the Order object. The inventory record itself is not directly related to the treatment record that is creating it - it is only by the order id. In simple form.

Inventory - child (what I am trying to insert via the trigger) Treatments - parent Visits - grand parent Work Order - great grand parent Orders - great great grand parent (Order ID from inventory comes from here)

Essentially I have a simple trigger as follows, ran on after insert via a trigger handler. It executes when i expect:

Apex code

public class TreatmentsActions {
    public static void createTreatmentInventory(List<Treatments__c> NewTreatments){     
        
        List<Inventory__c> InventoryToCreate = new list<Inventory__c>{};        

        for(Treatments__c t: NewTreatments) {
            InventoryToCreate.add(new Inventory__c( Product_InventoryLookup__c = t.product_treatmentlookup__c,
                                                   Quantity__c = t.Quantity__c * -1, Order__c = t.Visit__r.Work_Order__r.Order__r.Id ));
        }

        try {
                insert InventoryToCreate;
            }
            catch(DMLException e){
                System.debug('--------------Exception in createTreatmentInventory');
                System.debug('Exception occurred '+String.valueOf(e));
            }
  }   

}

As you probably expect the t.Visit__r.Work_Order__r.Order__r.Id and t.product_treatmentlookup__c are null. The record is not inserted.

I currently "think" it is down to context, the treatment record has id values for the visit and product fields but if I try and use system.debug to access the related fields (visits__r.work_order__r.order__r.id etc) I just receive nulls.

Edit: if I run the following SOQL "select visit__r.work_order__r.order__r.id FROM Treatments__c" it returns [object object] which maybe a console bug!?