Triggers
Triggers and classes are two fundamental building blocks in Apex. A trigger is a piece of code that executes automatically in response to specific events on a particular Salesforce object, such as insertions, updates, or deletions. It is used for automating tasks like updating related records or enforcing business rules.
Apex Class
On the other hand, an Apex class is a blueprint from which objects are created. It encapsulates data and behavior (methods) and is more about structuring code and reusability. Classes can be invoked by triggers, but they serve a broader purpose, providing a framework for the application logic.
Frequently Asked Questions
1. What is the difference between Apex classes and triggers?
Apex classes and Apex triggers serve different purposes in Salesforce. Apex classes are used to define objects and methods that encapsulate specific business logic, allowing for code reuse and modularity. They can contain variables, constructors, methods, and are used to create reusable pieces of code that can be called from various parts of your Salesforce application.
Apex triggers, on the other hand, are pieces of code that execute automatically in response to specific events on Salesforce records, such as insert, update, delete, and undelete operations. Triggers allow you to perform operations or enforce rules when these events occur, providing a way to automate complex business processes.
2. What is a trigger in Apex?
A trigger in Apex is a piece of code that executes automatically in response to specific events on Salesforce records. Triggers can be defined to run before or after events like insert, update, delete, and undelete. They allow developers to perform custom actions, such as validating data, updating related records, or executing complex business logic when changes occur to Salesforce records.
3. What is the difference between class and object in Apex?
In Apex, a class is a blueprint or template for creating objects. It defines the properties (variables) and behaviors (methods) that the objects created from the class will have. A class encapsulates data and methods that operate on that data.
An object is an instance of a class. It represents a specific realization of the class template, with actual values assigned to the class’s properties. For example, if you have a class called Account, an object would be an individual account record with specific details such as account name, account number, and so on.
4. Can we call a trigger from an Apex class?
Triggers cannot be called directly from an Apex class. Triggers are automatically executed by the Salesforce platform in response to specific DML events (insert, update, delete, undelete). However, you can invoke Apex methods from within a trigger to encapsulate and manage the business logic that should be executed when the trigger runs.
5. What is an Apex class?
An Apex class is a template or blueprint in Salesforce that defines the properties and methods common to objects of a certain kind. It encapsulates data and behaviors related to that data, allowing for the creation of reusable pieces of code. Apex classes can be used to write custom logic, integrate with external systems, and extend Salesforce’s built-in functionality. For example:
public class AccountHandler {
public void createAccount(String name) {
Account acc = new Account(Name = name);
insert acc;
}
}
6. Do Apex triggers need test classes?
Yes, Apex triggers need to be tested using test classes. Salesforce requires that all Apex code, including triggers, have a minimum of 75% code coverage from unit tests before it can be deployed to a production environment. Test classes are written to validate the functionality of the trigger, ensuring that it works as expected and handles various scenarios and edge cases.
7. How many triggers can you write in an Apex class?
Apex classes and Apex triggers are separate entities. You can write multiple triggers for different objects and events, but it is a best practice to have one trigger per object to avoid potential conflicts and to better manage the trigger logic. This practice is often referred to as the One Trigger Per Object pattern. In an Apex class, you do not write triggers directly, but you can define multiple methods to support the logic that a trigger calls.
8. Are Apex triggers synchronous or asynchronous?
Apex triggers are primarily synchronous, meaning they execute immediately in response to the data events that fire them (such as insert, update, delete). However, within a trigger, you can call asynchronous operations, such as future methods, queueable Apex, or batch Apex, to handle longer-running or more complex processes that do not need to be completed immediately.
9. How do you bypass a trigger in Apex class?
To bypass a trigger in Apex, you can use a static variable in a handler class to control whether the trigger logic should run. Here’s an example:
public class TriggerHandler {
public static Boolean bypassTrigger = false;
}
trigger AccountTrigger on Account (before insert, before update) {
if (TriggerHandler.bypassTrigger) {
return;
}
// Trigger logic here
}
When you need to bypass the trigger, set TriggerHandler.bypassTrigger to true in your Apex class:
TriggerHandler.bypassTrigger = true;
// Perform DML operation that bypasses the trigger
TriggerHandler.bypassTrigger = false;
10. Can we schedule a class from an Apex trigger?
Scheduling a class from an Apex trigger directly is not recommended due to the potential for high complexity and governor limit issues. However, you can indirectly schedule a class by calling a method within the trigger that schedules an Apex job using the System.schedule method. Here’s an example:
public class ScheduledJob implements Schedulable {
public void execute(SchedulableContext sc) {
// Job logic here
}
}
trigger AccountTrigger on Account (after insert) {
if (Trigger.isAfter && Trigger.isInsert) {
String jobName = 'ScheduledJob' + System.currentTimeMillis();
String cronExp = '0 0 0 * * ?'; // Schedule for midnight daily
System.schedule(jobName, cronExp, new ScheduledJob());
}
}
11. How do I stop Apex triggers?
To stop or disable an Apex trigger, you can temporarily deactivate it by commenting out the trigger body or using custom logic to bypass it based on a condition. However, Salesforce does not provide a direct way to disable triggers through the UI. For a more controlled approach, you can use custom settings or custom metadata types to enable or disable triggers dynamically.
12. Can we trigger a flow from an Apex class?
Yes, you can trigger a flow from an Apex class using the Flow.Interview class. This allows you to start a flow programmatically. Here’s an example:
Map<String, Object> flowInputs = new Map<String, Object>();
flowInputs.put('inputVar1', 'Value1');
flowInputs.put('inputVar2', 'Value2');
Flow.Interview myFlow = new Flow.Interview('FlowApiName', flowInputs);
myFlow.start();
In this example, FlowApiName is the API name of the flow you want to start, and flowInputs is a map of input variables required by the flow. This enables you to integrate flows with your Apex logic seamlessly.
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