Salesforce App Builder Practice Exam

Creating a before trigger and validating the value using APEX code is the best method for this scenario because it allows for real-time validation of the custom field before the order is saved to the database. Since triggers execute before or after a record is saved, a before trigger provides the opportunity to check the field value against a predefined list of ISO countries and prevent the operation from proceeding if the validation fails. This direct approach ensures that only valid data is stored in the database, maintaining data integrity from the outset.

Additionally, implementing this logic in APEX code allows for greater flexibility, as the developer can handle more complex validation scenarios, such as accessing external resources or using advanced data structures that may be impractical with simple validation rules.

While using a validation rule is an option, it would typically work well for straightforward checks and validations that can be directly expressed in a formula. The complexity and potential size of the ISO countries' list might exceed the limitations or versatility of validation rules. Furthermore, using an after trigger would not be appropriate in this case, as it wouldn't prevent the order from being saved with an invalid value; it would only allow the system to react after the fact, which is not ideal for maintaining the quality of data upon initial entry.