6.2 Introducing Kevin O’hara’s Trigger handler framework

In our last post, we have introduced the benefit of having a TriggerHandler framework. In this post, we are gonna introduce Kevin O’hara’s framework.

This framework is which I have been currently use in my various projects. I highly recommend this framework to everyone. It’s lightweight and open source. It has all those cool features a good TriggerHandler can offer.

The Github page is here.

Usage

To create a trigger handler, you simply need to create a class that inherits from TriggerHandler.cls. Here is an example for creating an Opportunity trigger handler.

public class OpportunityTriggerHandler extends TriggerHandler {

In your trigger handler, to add logic to any of the trigger contexts, you only need to override them in your trigger handler. Here is how we would add logic to a beforeUpdate trigger.

public class OpportunityTriggerHandler extends TriggerHandler {
  
  public override void beforeUpdate() {
    for(Opportunity o : (List<Opportunity>) Trigger.new) {
      // do something
    }
  }

  // add overrides for other contexts

}

Note: When referencing the Trigger statics within a class, SObjects are returned versus SObject subclasses like Opportunity, Account, etc. This means that you must cast when you reference them in your trigger handler. You could do this in your constructor if you wanted.

public class OpportunityTriggerHandler extends TriggerHandler {

  private Map<Id, Opportunity> newOppMap;

  public OpportunityTriggerHandler() {
    this.newOppMap = (Map<Id, Opportunity>) Trigger.newMap;
  }
  
  public override void afterUpdate() {
    //
  }

}

To use the trigger handler, you only need to construct an instance of your trigger handler within the trigger handler itself and call the run() method. Here is an example of the Opportunity trigger.

trigger OpportunityTrigger on Opportunity (before insert, before update) {
  new OpportunityTriggerHandler().run();
}

Cool Stuff

Max Loop Count

To prevent recursion, you can set a max loop count for Trigger Handler. If this max is exceeded, and exception will be thrown. A great use case is when you want to ensure that your trigger runs once and only once within a single execution. Example:

public class OpportunityTriggerHandler extends TriggerHandler {

  public OpportunityTriggerHandler() {
    this.setMaxLoopCount(1);
  }
  
  public override void afterUpdate() {
    List<Opportunity> opps = [SELECT Id FROM Opportunity WHERE Id IN :Trigger.newMap.keySet()];
    update opps; // this will throw after this update
  }

}

Bypass API

What if you want to tell other trigger handlers to halt execution? That’s easy with the bypass api. Example.

public class OpportunityTriggerHandler extends TriggerHandler {
  
  public override void afterUpdate() {
    List<Opportunity> opps = [SELECT Id, AccountId FROM Opportunity WHERE Id IN :Trigger.newMap.keySet()];
    
    Account acc = [SELECT Id, Name FROM Account WHERE Id = :opps.get(0).AccountId];

    TriggerHandler.bypass('AccountTriggerHandler');

    acc.Name = 'No Trigger';
    update acc; // won't invoke the AccountTriggerHandler

    TriggerHandler.clearBypass('AccountTriggerHandler');

    acc.Name = 'With Trigger';
    update acc; // will invoke the AccountTriggerHandler

  }

}

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