Trigger.new List During a Transaction

Question

This is a question I have always wondered. I have a series of classes and methods that modify the Trigger.new case list records as the list is handed off to each class and method.

Apex goes down the lines of classes and methods synchronously in the trigger. I assume after each class and method changes trigger.new (field values updated, etc.), it then hands the new list of case records to the next class and method(s) and so on.

I assume the original unmodified trigger.new list is not handed to the next class or method, the modified one in is.

That is my understanding of how the transaction works. I ask this to prevent my cobweb of classes and methods from becoming too dependent on the order of execution within each trigger context variable.

trigger CaseTrigger on Case (before insert) {

if(Trigger.isBefore) {
   if(Trigger.isInsert) {

        QualifyCase.QualifyRecordType(Trigger.new);
        ProcessCase.ConvertChars(Trigger.new);
        RouteCase.DetermineOwner(Trigger.new);

    }
  }    
}

Answer 1

The collection itself remains the same, but the context records are modified. Consider the following contrived example:

Service Layer

public with sharing class MyObjectService
{
    public static void setTextField1(List<MyObject__c> records)
    {
        for (MyObject__c record : records)
        {
            record.Field1__c = 'Hello';
        }
    }
    public static void setTextField2(List<MyObject__c> records)
    {
        for (MyObject__c record : records)
        {
            record.Field2__c = 'World';
        }
    }
    public static void setTextField3(List<MyObject__c> records)
    {
        for (MyObject__c record : records)
        {
            record.Field3__c = record.Field1__c + record.Field2__c;
        }
    }
}

Trigger

trigger MyObject on MyObject__c (before insert)
{
    if (trigger.isBefore)
    {
        if (trigger.isInsert)
        {
            MyObjectService.setTextField1(trigger.new);
            MyObjectService.setTextField2(trigger.new);
            MyObjectService.setTextField3(trigger.new);
        }
    }
}

In this example, when you call setTextField2, each record being processed will have Field1__c already set to 'Hello'. Then when you call setTextField3, both Field1__c and Field2__c will already be set, so Field3__c should equal 'HelloWorld' for each record.