Understanding Apex Triggers in Salesforce
An Apex Trigger is server-side Apex code that executes before or after specific data manipulation language (DML) events on Salesforce records. Triggers allow developers to perform custom actions — such as validation, record updates, or integrations — when records are inserted, updated, deleted, or undeleted. Apex Triggers run as part of the Salesforce transaction and participate in the platform’s order of execution.
Key characteristics
– Executed in response to DML events (insert, update, delete, undelete).
– Can run before or after the DML event.
– Run in the system context (ignores user permissions for Apex unless explicitly enforced).
– Subject to Salesforce governor limits and best-practice patterns.
When should you use an Apex Trigger?
Use Apex Triggers when the required business logic cannot be implemented using declarative tools (Flows, Process Builder, Workflow Rules) or when the logic must run as part of the same transaction to maintain data integrity. Typical scenarios include:
1. Complex multi-record logic
If you need to process collections of records, perform cross-object calculations, or update multiple related records in one transaction, Apex trigger code that bulkifies logic is the right choice. Declarative tools often struggle with complex bulk operations or performance when handling many records.
2. Advanced validation or conditional processing
When validation rules are not sufficient — for example, validations that require querying related objects, calling utility methods, or evaluating historical data — triggers provide the flexibility to implement those validations in Apex.
3. Integration or callouts as part of record processing
When a record change must cause synchronous or asynchronous integration work (callouts, queuable jobs, platform events) that is tightly coupled with the transaction, a trigger can enqueue asynchronous work or call helper classes. Note: callouts cannot be made directly from triggers; you must use asynchronous Apex (Queueable, Future) invoked from the trigger.
4. Custom complex rollback or transaction control
Triggers run within the transaction and can throw exceptions to roll back operations if business rules fail. When the requirement is to ensure atomicity across multiple records and objects, triggers ensure changes are either committed together or rolled back.
5. When declarative automation cannot meet ordering or timing requirements
Salesforce’s order of execution and the relative order of declarative automations (Flows, Process Builders) can be complex. If you need precise control over when logic runs relative to the DML event (before vs after) and other automations, Apex Triggers provide explicit control.
Trigger Types & Examples
Triggers can be defined for before insert, before update, after insert, after update, before delete, after delete, and after undelete. Use:
- Before triggers to validate or modify record values before they are committed (to avoid extra DML).
- After triggers to access record IDs, create related records, or perform operations that require the record to exist in the database.
Sample (bulkified) trigger pattern
trigger AccountBeforeInsert on Account (before insert) {
// Call a handler class for bulkified logic
AccountTriggerHandler.beforeInsert(Trigger.new);
}
Recommended handler class structure (concept)
public class AccountTriggerHandler {
public static void beforeInsert(List
// Bulkified logic, avoid SOQL/DML inside loops
// e.g., set defaults, validate, aggregate
}
}
Best Practices when using Apex Triggers
– Bulkify all logic: operate on collections, not single records.
– Use a trigger handler framework to keep triggers thin and maintainable.
– Minimize SOQL and DML, combine queries, and use maps/sets.
– Avoid recursive trigger calls by using static variables or a proper control pattern.
– Prefer declarative automation when it meets requirements — Apex only when necessary.
– Respect governor limits: use asynchronous processing for long-running tasks.
Common Alternatives
Before writing a trigger, evaluate declarative tools:
– Flow Builder: powerful for many record-changing automations without code.
– Process Builder / Workflow Rules: legacy tools, less recommended for new work.
Choose Apex only when declarative solutions cannot provide the required flexibility, performance, or transactional behavior.
Conclusion
Apex Triggers are a powerful tool for executing custom business logic on record DML events in Salesforce. Use them when you need fine-grained control, multi-record processing, complex validations, or integration steps that declarative tools cannot reliably handle. Always follow bulkification and trigger-handler patterns to build scalable, maintainable solutions.