2503 Trigger Deployment Safety 99489e5d

Trigger Deployment Safety Guide

💡 Principles inspired by "Clean Apex Code" by Pablo Gonzalez. Purchase the book for complete coverage.

Overview

This guide covers deployment considerations for triggers, focusing on cascade failures, atomicity patterns, and async decoupling strategies.

1. Understanding Cascade Failures

What Are Cascade Failures?

When an exception in one trigger causes rollback of operations from preceding triggers in the chain.

Account Insert → AccountTrigger → ContactTrigger → OpportunityTrigger
                     ✓               ✓                 ✗ (Exception)

                 All three operations ROLL BACK

Default Behavior

• Uncaught exceptions in triggers cause rollback of all operations in the transaction
• This includes operations from other triggers that fired successfully
• This behavior may or may not be desired depending on business requirements

When Cascade Failure is DESIRED

• All operations represent ONE atomic business process
• Example: Order with line items must be complete or not exist
• Same business unit/persona owns all the data

// DESIRED cascade: Order and OrderItems must both succeed
trigger OrderTrigger on Order__c (after insert) {
    // If this fails, we WANT the Order insert to roll back
    List<OrderItem__c> items = createDefaultLineItems(Trigger.new);
    insert items;  // Exception here rolls back Order insert - GOOD
}

When Cascade Failure is PROBLEMATIC

• Operations represent INDEPENDENT business processes
• Example: Creating account + syncing to external CRM
• Different business units own different parts of the process

// PROBLEMATIC cascade: CRM sync failure shouldn't prevent Account creation
trigger AccountTrigger on Account (after insert) {
    // If CRM sync fails, Account creation also fails - BAD
    CRMService.syncNewAccounts(Trigger.new);  // Exception here rolls back Account
}

2. Atomicity Patterns

Explicit Savepoints

Use Database.setSavepoint() for explicit transaction control within a single process.

/**
 * Demonstrates explicit atomicity control for cross-object operations
 */
public class AccountOwnership {

    /**
     * Reassigns all related records when account owner changes.
     * This is an ATOMIC operation - all changes succeed or all roll back.
     */
    public static void reassignRelatedRecords(
        List<Account> accountsWithNewOwner,
        Map<Id, Account> oldAccountsById
    ) {
        // Create savepoint for atomic operation
        Savepoint sp = Database.setSavepoint();

        try {
            Map<Id, Id> newOwnerByAccountId = buildOwnerMap(accountsWithNewOwner);

            // Step 1: Reassign opportunities
            reassignOpportunities(newOwnerByAccountId);

            // Step 2: Reassign cases
            reassignCases(newOwnerByAccountId);

            // Step 3: Create transition tasks
            createOwnerTransitionTasks(accountsWithNewOwner, oldAccountsById);

        } catch (Exception e) {
            // Rollback ALL changes if ANY step fails
            Database.rollback(sp);

            // Log the failure for investigation
            ErrorLogger.log('AccountOwnership.reassignRelatedRecords', e);

            // Re-throw to inform the caller
            throw new AccountOwnershipException(
                'Failed to reassign related records: ' + e.getMessage()
            );
        }
    }
}

When to Use Savepoints

3. Async Decoupling Patterns

The Problem

After-trigger logic that represents an independent business process can cause cascade failures.

Solution: Queueable Jobs

/**
 * Queueable job for processing that should not block the main transaction
 */
public class AccountSyncQueueable implements Queueable, Database.AllowsCallouts {

    private Set<Id> accountIds;
    private TriggerOperation operationType;

    public AccountSyncQueueable(Set<Id> accountIds, TriggerOperation operationType) {
        this.accountIds = accountIds;
        this.operationType = operationType;
    }

    public void execute(QueueableContext context) {
        try {
            List<Account> accounts = [
                SELECT Id, Name, Website, Industry, BillingAddress
                FROM Account
                WHERE Id IN :accountIds
            ];

            switch on operationType {
                when AFTER_INSERT {
                    ExternalCRM.createAccounts(accounts);
                }
                when AFTER_UPDATE {
                    ExternalCRM.updateAccounts(accounts);
                }
                when AFTER_DELETE {
                    ExternalCRM.deleteAccounts(accountIds);
                }
            }

        } catch (Exception e) {
            // Log error but don't fail - this is independent of main transaction
            ErrorLogger.log('AccountSyncQueueable', e, accountIds);
        }
    }
}

Usage in Trigger Handler

public void afterInsert(List<Account> newAccounts, Map<Id, Account> newAccountsById) {
    // Synchronous operations that SHOULD block
    AccountNotifications.notifySalesTeam(newAccounts);

    // Async operations that should NOT block main transaction
    if (canEnqueueJob()) {
        System.enqueueJob(new AccountSyncQueueable(
            newAccountsById.keySet(),
            TriggerOperation.AFTER_INSERT
        ));
    }
}

private Boolean canEnqueueJob() {
    return !System.isBatch() &&
           !System.isFuture() &&
           Limits.getQueueableJobs() < Limits.getLimitQueueableJobs();
}

Platform Events for Maximum Decoupling

// Publisher (in trigger)
EventBus.publish(new Account_Changed__e(
    Account_Id__c = account.Id,
    Change_Type__c = 'INSERT'
));

// Subscriber (separate trigger on platform event)
trigger AccountChangedSubscriber on Account_Changed__e (after insert) {
    // Process events - failures here don't affect original transaction
    List<Id> accountIds = new List<Id>();
    for (Account_Changed__e event : Trigger.new) {
        accountIds.add(event.Account_Id__c);
    }
    // Sync to external system
}

Decoupling Decision Matrix

4. Pre-Deployment Checklist

Trigger Cascade Analysis

Before deploying triggers, analyze the cascade impact:

CHECKLIST:
□ List all triggers that fire on the same transaction
□ Identify which operations are atomic (same business process)
□ Identify which operations are independent (different processes)
□ Verify exception handling in each trigger
□ Check for recursive trigger prevention
□ Review async job usage and limits

Questions to Answer

1. What triggers will fire together?

   • Map the full trigger chain for each DML operation
   • Include triggers on related objects (parent-child)

2. What happens if each trigger fails?

   • Which operations will roll back?
   • Is that the desired behavior?

3. Are there external system calls?

   • Should they be async?
   • What happens if they fail?

4. What about governor limits?

   • How many DML statements in the chain?
   • How many SOQL queries?
   • Can bulk operations stay within limits?

5. Testing Cascade Scenarios

Test Cascade Success

@IsTest
static void testTriggerChain_AllSucceed() {
    Test.startTest();
    Account acc = new Account(Name = 'Test');
    insert acc;  // Should fire AccountTrigger, create child records, etc.
    Test.stopTest();

    // Verify all expected records were created
    Assert.areEqual(1, [SELECT COUNT() FROM Contact WHERE AccountId = :acc.Id]);
    Assert.areEqual(1, [SELECT COUNT() FROM Task WHERE WhatId = :acc.Id]);
}

Test Cascade Failure (Expected Rollback)

@IsTest
static void testTriggerChain_ChildFailure_RollsBack() {
    // Configure scenario that will cause child trigger to fail
    Test.startTest();
    try {
        Account acc = new Account(Name = 'Trigger Failure Test');
        insert acc;
        Assert.fail('Expected DmlException');
    } catch (DmlException e) {
        // Expected - verify Account was NOT created
        Assert.areEqual(0, [SELECT COUNT() FROM Account WHERE Name = 'Trigger Failure Test']);
    }
    Test.stopTest();
}

Test Async Decoupling

@IsTest
static void testAccountInsert_CRMSyncAsync_DoesNotBlock() {
    // Even if CRM sync would fail, Account should be created
    Test.startTest();
    Account acc = new Account(Name = 'Async Test');
    insert acc;
    Test.stopTest();

    // Account should exist regardless of async job outcome
    Assert.areEqual(1, [SELECT COUNT() FROM Account WHERE Name = 'Async Test']);

    // Verify async job was enqueued
    Assert.areEqual(1, [SELECT COUNT() FROM AsyncApexJob WHERE JobType = 'Queueable']);
}

6. Deployment Commands for Trigger Safety

Validate Before Deploying

# Always validate triggers before deploying
sf project deploy start --dry-run \
    --source-dir force-app/main/default/triggers \
    --source-dir force-app/main/default/classes \
    --test-level RunLocalTests \
    --target-org alias

Deploy with Test Coverage

# Deploy triggers with their test classes
sf project deploy start \
    --source-dir force-app/main/default/triggers \
    --source-dir force-app/main/default/classes \
    --test-level RunSpecifiedTests \
    --tests AccountTriggerTest,ContactTriggerTest \
    --target-org alias

Verify Trigger Order

After deployment, verify trigger execution order if you have multiple triggers on the same object:

# Query trigger execution order (via Debug Logs)
sf apex log tail --target-org alias

# Or check in Setup: Object Manager → [Object] → Triggers

Summary

Key Principles

1. Make atomicity decisions explicit - Don't rely on default behavior accidentally
2. Decouple independent processes - Use async for cross-domain operations
3. Test cascade scenarios - Verify both success and failure paths
4. Document trigger chains - Future maintainers need to understand dependencies
5. Validate before deploying - Use --dry-run to catch issues early