[SalesForce] Update same record in after insert/update in a trigger context

I searched a bit for some informations about the need to make an update on a record in after insert/update trigger context.
I found that the common feedback was to move the Business logic in before context, which is a best practice most of the times.

Anyway, As a programmer I would understand how to execute an update in after insert/update context

this because the formula field are updated
I can be sure that all the before operations has processed properly and without issues.

In this situation what I have to keep in mind so to avoid issues?
With the new DML I'm going to fire a new trigger (before and after), and we hve two triggers on same records that execute in the same context. So what happen to the variables:

Trigger.Old
Trigger.New

Those are the new variables or the first trigger, or the variables of the second trigger?

How can I controll/master the operations of the two triggers (and avoid an infinite loop )

I'm writing this question so to get a better explaination of this situation, I figured out that there is a poor documentation.

thnks in advance.

Best Answer

In a Before Trigger, Trigger.new and Trigger.old both contain the same values. However, in a Before Trigger, one can operate on the values in Trigger.new and change their values.

In an After Trigger, Trigger.new will contain the the Id's and field values of any records that have been changed by a DML operation. The values contained in Trigger.new can be compared to Trigger.old in order to determine which records meet the criteria for firing the trigger and need to be operated on. Unlike in a Before Trigger, the values in Trigger.new cannot be changed or edited.

Recursion is frequently handled by setting a boolean static variable to "true" when a trigger initially fires. Upon entry to the trigger, that static variable is tested. If the boolean is "true" when re-entered in the same execution context, then the trigger is exited rather than allowing it to run again. There are a variety of methods for handling recursion and this is probably the most common.

Edit

I think what you're looking for are trigger patterns such the one described by Dan Appleman in his book Advanced Apex Programming for Salesforce and Force.com (Note: sample code available from App Exchange as an unmanaged package), Hari Krishan's Architecture Framework to Handle Triggers or Kevin O'Hara's Trigger Framework among others that exist or have been espoused which you can find through searching that go beyond the Trigger Pattern for Tidy, Streamlined, Bulkified Triggers.

Using a Main Dispatcher class, these approaches take charge of trigger execution, extending it to an enterprise level application that's scalable, can have it's own diagnostics classes and error reporting, utilize common helper classes and much more. One can also control trigger execution order; something that can't be done with triggers that operate independently of one other without some kind of central control for each object or, as is the case with some architures, potentially for related objects as well.

Discussing them in depth is beyond the scope of this forum, but I'll point you to at least a few posts that you may find relevant including: Controlling Trigger Execution, One Trigger Approach: Any Logic in Trigger?, Difficulties with Appleman's Trigger Classes and General trigger bulkification - best practices.

Related Solutions

[SalesForce] Trigger to create new event after insert/update creating dupes

Most likely the cause is either

You have a second trigger somewhere else in your code base on Handoff__c that in turn does a DML update on itself or
You have a field update on Handoff__c via a workflow that will cause the after update trigger to be reinvoked.

You can resolve either of these by using the controlling recursive triggers recipe as shown in the SFDC doc here or here in Help doc. You may also be able to control it by tighter if statements to avoid creating the Events even if invoked twice.

This SFSE post addresses workflows and updates of greater than 200 records

Lastly, examine your debug log to see where the after update trigger on Handoff__c gets reinvoked, this may provide additional insight

[SalesForce] Is it possible to write Trigger for Before & After DML

It is quite possible, and in fact recommended (if you need trigger logic on both events).

See also:

A common pattern is to have three separate layers of code: the trigger itself, a handler, and a service layer. Here's the trigger framework I prefer.

Trigger

trigger CaseTrigger on Case (after insert)
{
    EventTriggerHandler handle = new EventTriggerHandler(trigger.new, trigger.oldMap);

    if (trigger.isBefore)
    {
        if (trigger.isInsert) handle.beforeInsert();
        if (trigger.isUpdate) handle.beforeUpdate();
        // etc
    }
    if (trigger.isAfter)
    {
        if (trigger.isInsert) handle.afterInsert();
        if (trigger.isUpdate) handle.afterUpdate();
        // etc
    }
}

Handler

public with sharing class EventTriggerHandler
{
    @TestVisible static Boolean bypassTrigger = false;

    final List<Event> newRecords;
    final Map<Id, Event> oldMap;
    public EventTriggerHandler(List<Event> newRecords, Map<Id, Event> oldMap)
    {
        this.newRecords = newRecords;
        this.oldMap = oldMap;
    }

    public void beforeInsert()
    {
        if (bypassTrigger) return;

        CaseService.doStuff1();
    }
    public void afterInsert()
    {
        if (bypassTrigger) return;

        CaseService.doStuff2();
    }

    public void beforeUpdate()
    {
        if (bypassTrigger) return;

        CaseService.doStuff1();
    }
    public void afterUpdate()
    {
        if (bypassTrigger) return;

        CaseService.doStuff3();
    }
}

Service

public with sharing class CaseService
{
    public static void doStuff1() { /* "how" implementation */ }
    public static void doStuff2() { /* "how" implementation */ }
    public static void doStuff3() { /* "how" implementation */ }
}

Best Answer

Related Solutions

[SalesForce] Trigger to create new event after insert/update creating dupes

[SalesForce] Is it possible to write Trigger for Before & After DML

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