Triggers in Salesforce

⚙️ Writing Triggers in Apex

Triggers are essential for automating logic in Salesforce. They run before or after DML operations on records and allow you to enforce business rules at the database level.

---

🕐 Before vs After Triggers

• Before Triggers: Used to modify record values before saving to the database.
• After Triggers: Used when you need the record's ID or want to perform operations on related records.

Trigger Type	Use Case
before insert	Set default values before saving
after insert	Log creation, send notifications
before update	Validate or modify updates
after update	Act on changes with old/new values
before delete	Prevent deletion with custom checks
after delete	Clean up related records
after undelete	Re-link relationships after restore

---

🎯 Trigger Events

Triggers can fire on the following DML events:

• before insert
• after insert
• before update
• after update
• before delete
• after delete
• after undelete

---

📐 Trigger Design Pattern

The recommended pattern is One Trigger Per Object and delegate logic to a handler class.

AccountTrigger.trigger

trigger AccountTrigger on Account (before insert, after update) {
    AccountTriggerHandler.run(Trigger.isBefore, Trigger.isAfter);
}
  

AccountTriggerHandler.cls

public class AccountTriggerHandler {
    public static void run(Boolean isBefore, Boolean isAfter) {
        if (isBefore && Trigger.isInsert) {
            // Call helper logic
        } else if (isAfter && Trigger.isUpdate) {
            // Call helper logic
        }
    }
}
  

---

💡 Bulkification

Triggers should handle bulk operations (up to 200 records). Avoid SOQL/DML inside loops.

Bad Practice ❌

for (Account acc : Trigger.new) {
    insert new Contact(LastName = acc.Name + ' Contact');
}
  

Good Practice ✅

List newContacts = new List();
for (Account acc : Trigger.new) {
    newContacts.add(new Contact(LastName = acc.Name + ' Contact'));
}
insert newContacts;
  

---

🔁 Handling Recursion

To prevent infinite loops, use a static variable in a utility class.

TriggerControl.cls

public class TriggerControl {
    public static Boolean isFirstRun = true;
}
  

Usage in Trigger

if (TriggerControl.isFirstRun) {
    TriggerControl.isFirstRun = false;
    // Call logic
}
  

---

🧭 Order of Execution

1. Validation rules
2. Before triggers
3. Duplicate rules
4. Record saved (but not committed)
5. After triggers
6. Assignment rules, workflow, process builder
7. Roll-up summary, escalation
8. Commit to DB
9. Post-commit logic: emails, queueable, etc.

---

✅ Summary Tips

• Use one trigger per object
• Always bulkify your code
• Use handler classes for logic
• Guard against recursion
• Understand the order of execution