Order of Execution of Triggers in Apex

In our previous blog post we had discussed about Recursive Triggers in Salesforce Apex. In these blog post we discuss about Order of Execution of Triggers in Apex

Order of Execution of Triggers in Apex

What Are Apex Triggers

Before diving into the order of execution, let’s start with the basics: what exactly are Apex Triggers? In Salesforce, an Apex Trigger is a block of code that automatically runs when certain conditions are met in the database. These conditions are typically related to DML (Data Manipulation Language) events, such as Insert, Update, or Delete.

Types of Triggers in Apex

There are two main types of triggers in Salesforce:

• Before Triggers: These run before a record is saved to the database.
• After Triggers: These run after the data has been committed to the database.

Use Cases of Apex Triggers

Triggers are commonly used to enforce complex business rules, automate workflows, or even maintain data integrity. For example:

• Validation: Ensuring certain conditions are met before inserting or updating a record.
• Automation: Automatically creating a related record or sending notifications when an event occurs.

The Importance of Trigger Execution Order

The sequence in which Salesforce executes triggers is not arbitrary. Salesforce uses a defined order of execution, and understanding this order is crucial to ensuring your business logic runs correctly.

Avoiding Unpredictable Behavior

If you’re unaware of the order in which triggers and workflows are executed, you risk introducing unpredictable behavior into your Salesforce org. Imagine updating a record in an After Insert trigger only to realize that Validation Rules fire before your changes are saved. That would likely cause confusion, errors, or both.

Handling Recursion and Efficiency

Knowing the order of execution also helps developers avoid recursion—where triggers accidentally call themselves over and over—or creating inefficient code that eats into Salesforce’s governor limits.

Overview of the Order of Execution in Salesforce

Let’s explore what happens before and after triggers fire in Salesforce.

What Happens Before Triggers Fire

Before a trigger is executed, Salesforce performs several background operations:

• Loading the Original Record: For an insert or update operation, Salesforce loads the original version of the record from the database.
• System Validation Rules: Salesforce checks field values against built-in validation rules to ensure they comply with the database schema.

What Happens After Triggers Fire

After a trigger completes, Salesforce may fire additional automation processes, like Workflow Rules or Approval Processes, based on the outcome of the trigger logic.

Detailed Steps in the Order of Execution of Triggers

Now, let’s walk through each step of the trigger execution order in detail.

Loading Original Record for Insert, Update

Before anything else, Salesforce loads the original version of the record if it’s an update, or it prepares a new record if it’s an insert operation.

System Validation Rules

Next, the system performs system validation. This step ensures that mandatory fields have values and that field values match their data types.

Before Trigger

In this step, Salesforce fires Before Triggers. These triggers allow you to modify record values before they are saved to the database.

Custom Validation Rules

After the Before Triggers complete, Salesforce runs any Custom Validation Rules you’ve defined. These rules are usually written to enforce business-specific data integrity.

After Trigger

Once validation is complete, After Triggers are fired. These triggers can no longer modify the record’s data directly, but they can create related records, send notifications, or perform other actions.

Assignment Rules

If your object supports them, Assignment Rules—like for Leads or Cases—run next, ensuring the record is routed to the appropriate user or queue.

Workflow and Process Automation

After assignment rules, Workflow Rules and Processes defined in Process Builder or Flow run. They can modify the record, create related records, or execute actions like email alerts.

Escalation and Entitlement Rules

If applicable, Escalation Rules or Entitlement Rules are applied, which help manage service-level agreements (SLAs) or escalate cases.

Post-Commit Logic

Finally, after the transaction is fully committed to the database, post-commit logic such as Send Email actions or Outbound Messages are executed.

Best Practices for Managing Trigger Execution

To prevent issues with trigger execution, here are a few best practices.

One Trigger Per Object

Always aim to have one trigger per object. You can use trigger frameworks to break logic into smaller, manageable pieces while avoiding multiple triggers that cause unpredictable execution sequences.

Trigger Frameworks and Handlers

Using a Trigger Framework helps in organizing your code. A popular approach is the Trigger Handler Pattern, where you separate the trigger logic into handler classes for modularity and clarity.

Common Mistakes and How to Avoid Them

Here are a few common pitfalls developers run into when working with triggers and how to avoid them.

Trigger Recursion

Recursion happens when one trigger causes another trigger to fire, which can lead to infinite loops. You can prevent this by using static variables to ensure a trigger only runs once per transaction.

Managing Governor Limits

Salesforce imposes Governor Limits to ensure that no single transaction monopolizes system resources. Be mindful of how many SOQL queries or DML operations you’re executing in a single transaction.

Conclusion

Understanding the order of execution of triggers in Apex is vital to ensure your Salesforce code behaves as expected. By following the defined execution flow, using best practices, and avoiding common mistakes, you can ensure that your Apex Triggers perform optimally and reliably.

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FAQs

What is the purpose of Before Triggers in Salesforce?
Before Triggers allow you to make changes to a record before it’s saved to the database, ensuring data integrity.

How do I prevent trigger recursion in Salesforce?
You can prevent recursion by using static variables that track whether the trigger has already fired during the current transaction.

What are Assignment Rules in Salesforce?
Assignment Rules are used to automatically assign records to users or queues, often used for Leads and Cases.

Can I modify records in an After Trigger?
No, After Triggers cannot modify the same record that caused the trigger to fire, but they can create related records or perform other actions.

What are Governor Limits, and why do they matter?
Governor Limits are Salesforce’s way of ensuring that no single transaction consumes too many system resources, which could negatively impact other users.

In our next blog post we will discuss about Future Annotation in Apex