I'm trying to write a simple trigger that renames a record. I keep getting the error "CallLineItemRename: execution of BeforeInsert caused by: System.SObjectException: DML statment cannot operate on trigger.new or trigger.old: Trigger.CallLineItemRename: line 18, column 9" . What am I missing here?

 

 

 

trigger CallLineItemRename on Call_Line_Item__c (before insert, before update) { // this triger renames the call line item id to be // the specified inventory item name or the product name List<Call_Line_Item__c> callItems = new List<Call_Line_Item__c>(); callItems = Trigger.new; for (Call_Line_Item__c callItem : callItems) { //check if inventory or product was specified if (callItem.Inventory_Item__c <> NULL) { callItem.Name = callItem.Inventory_Item__r.Name; callItem.Name = 'inv item name'; } else if (callItem.Products__c <> NULL) { callItem.Name = callItem.Products__r.Name; } } update callItems; }