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03 · The handler pattern

One method per event, a static bypass flag, and constructor-free classes your tests will thank you for.

Article 15m 1 min read Updated 14 Jul 2025
03 · The handler pattern
Modules
Apex Triggers
  1. Module overview
  2. 01 · Order of execution, the map
  3. 02 · One trigger per object
  4. 03 · The handler pattern
  5. 04 · Bulkification: 200 records or bust
  6. 05 · Recursion control
Data Model Basics
  1. Module overview
  2. 01 · Standard objects vs custom objects
  3. 02 · Relationship types, decided with three questions
  4. 03 · Record types and when not to use them
  5. 04 · Schema Builder, the honest map
  6. 05 · Junction objects in practice
Integration Patterns
  1. Module overview
  2. 01 · Request-reply with named credentials
  3. 02 · Fire-and-forget with platform events
  4. 03 · Batch sync without tears
  5. 04 · Middleware or point-to-point?
  6. 05 · Watch: a callout built end to end

One method per event, a static bypass flag, and constructor-free classes your tests will thank you for.

The shape

beforeInsert(newList), afterUpdate(oldMap, newMap) — the trigger passes context variables straight through. The handler owns every decision; the trigger owns nothing.

The bypass flag

A public static Boolean lets data migrations and tests switch the handler off without touching metadata. Use sparingly; log every use.

Practice in your org

  • Open your Developer Edition org and follow along step by step
  • Change one thing at a time and note what happens
  • When something breaks, read the error before searching for it