What's the Difference Between Apex Triggers and Apex Classes?

Apex Triggers and Apex Classes are both critical components in Salesforce development, but they serve different purposes and are used in distinct contexts. Here’s how to understand their differences.

Apex Triggers

Purpose:

• Apex Triggers are designed to automate processes by executing custom actions before or after changes to Salesforce records. They are event-driven, meaning they run in response to specific data changes like insertions, updates, deletions, or undeletes of records.

When to Use:

• When you need to perform operations directly tied to database actions (DML operations) such as creating, updating, or deleting records.
• To enforce business rules, maintain data integrity, or perform custom actions automatically when a record is modified.

Structure:

• Triggers are defined for specific Salesforce objects and have limited execution contexts: before or after insert, update, delete, or undelete.
• They contain trigger handlers that determine the logic to execute for the specified operations.

Execution Context:

• They run in the context of the DML operation on which they are triggered. This means they execute based on the actions performed on the records (e.g., insert, update).
• Triggers operate on a bulk basis, meaning they can handle multiple records at once in a single execution context.

Syntax Example:

trigger AccountTrigger on Account (before insert, after insert, before update, after update) {
    if (Trigger.isBefore) {
        if (Trigger.isInsert) {
            // Logic before inserting an Account
        }
        if (Trigger.isUpdate) {
            // Logic before updating an Account
        }
    }
    if (Trigger.isAfter) {
        if (Trigger.isInsert) {
            // Logic after inserting an Account
        }
        if (Trigger.isUpdate) {
            // Logic after updating an Account
        }
    }
}

Apex Classes

Purpose:

• Apex Classes are general-purpose containers for business logic and are used to define reusable code that can be called from various parts of the application. They can include methods, variables, and inner classes.

When to Use:

• When you need to encapsulate complex logic, perform calculations, or handle reusable operations that aren't directly tied to database events.
• To build services, utility functions, and logic that can be invoked by triggers, Visualforce pages, Lightning components, batch processes, or other Apex code.

Structure:

• Classes can have methods and properties, and they can implement interfaces or inherit from other classes.
• They provide a modular approach to development, allowing for the separation of concerns and the organization of code into logical units.

Execution Context:

• They can be called from triggers, other classes, or directly by users via buttons, batch processes, scheduled jobs, or web services.
• Classes are not tied to any specific event and provide more flexibility in how and when they are executed.

Syntax Example:

public class AccountHelper {
    public static void processNewAccounts(List<Account> newAccounts) {
        for (Account acc : newAccounts) {
            // Logic to process each new Account
            acc.Description = 'Processed by AccountHelper';
        }
    }

    public void updateAccountName(Account acc, String newName) {
        acc.Name = newName;
    }
}

Key Differences

Integration of Triggers and Classes

Best Practices:

• Separation of Concerns: Keep business logic within Apex classes and use triggers only to initiate these classes. This makes the code easier to manage and test.
• Reusable Code: Use classes to create reusable methods and utilities that can be called from multiple triggers or other components.
• Trigger Frameworks: Implement trigger frameworks that leverage classes to handle complex trigger logic, ensuring better organization and maintainability.

By understanding the distinct roles of Apex Triggers and Apex Classes, developers can effectively design and implement robust Salesforce solutions.

As always, please refer to the official Salesforce documentation here.

Next: When to use a trigger instead of a flow...