Creating a Handler

A handler extends ATriggerHandler and overrides only the context methods it needs. getType() is the only required override.

Splitting handlers

Think about the breakdown before writing a handler:

• One handler per related object or concern, for example TestObjectAccountHandler rather than one handler for everything.
• Don't duplicate a query across handlers that need the same data.
• Keep the DML for a given record in a single handler, not spread across several.

Handler shape

public with sharing class TestObjectHandler extends ATriggerHandler {
	// Optional. Omit to always run.
	public override Boolean shouldExecute() {
		return !FeatureManagement.checkPermission('Exclude_Trigger');
	}

	/**
	 * Required. Return the Type of the implementing class, e.g.
	 * TestObjectHandler.class.
	 */
	public override Type getType() {
		return TestObjectHandler.class;
	}

	/**
	 * Optional. Salesforce guarantees triggers fire once for insert and
	 * delete, but not for update. Override this and return true if the
	 * handler needs special double-fire protection on update.
	 */
	public override Boolean isDoubleFireSafe() {
		return false;
	}

	public override void beforeInsert(TriggerData triggerData) {
	}

	public override void afterInsert(TriggerData triggerData) {
	}

	public override void beforeUpdate(TriggerData triggerData) {
	}

	public override void afterUpdate(TriggerData triggerData) {
	}

	public override void beforeDelete(TriggerData triggerData) {
	}

	public override void afterDelete(TriggerData triggerData) {
	}

	public override void afterUndelete(TriggerData triggerData) {
	}
}

Add or remove the context methods based on what the Trigger_Handler__mdt record for this handler enables. An overridden method for a context the metadata record doesn't check off simply never runs.

Registering the handler

Create a Trigger_Handler__mdt record naming the handler class, and check off every trigger context it should participate in. Repeat for each new handler on the object.

Fields

A Use_* checkbox only has an effect if the matching context is also enabled on the handler's Trigger_Pipeline__mdt record; see Creating a pipeline for that side of the wiring. Overriding a context method in the class without checking the matching Use_* box here means the method is simply never called.