Understanding Salesforce Trigger Recursion

What is Trigger Recursion?

Trigger recursion happens when a Salesforce trigger calls itself, either directly or through another trigger. This can create loops where the same trigger keeps firing, which can lead to problems or even errors in your code.

Example of Recursion

Imagine you have a trigger on the Account object that updates related Contact records. If updating a Contact record causes the same Account trigger to run again, you've created a recursive situation. Here’s a quick look at what that might look like:

trigger AccountTrigger on Account (after update) {
    // Code to update Contacts goes here
    update contactsToUpdate; // This can trigger the same Account trigger again
}        

How to Prevent Recursion

To stop this from happening, you can use a static variable to check if the trigger has already run. Here’s how it works:

1. Static Variable: Create a variable that remembers whether the trigger has executed.
2. Check Before Running: Before executing the main logic of the trigger, check if it has already run.

public class TriggerHelper {
    public static Boolean isTriggerExecuted = false;
}

trigger AccountTrigger on Account (after update) {
    if (TriggerHelper.isTriggerExecuted) {
        return; // Exit if already run
    }

    TriggerHelper.isTriggerExecuted = true; // Mark as executed

    // Your trigger logic goes here
}