Appropriate Location for Validation Logic WIth the new Split Domain Layer

[bdJohnson72]

I like splitting out Trigger Handler logic from the domain class. But I wanted to ask if there was a sense of where actual validation and default code logic should live. If my ContactTriggerHandler calls its onValidate() method, should that validation logic be a part of ContactTriggerHandler, or should it be making a call to the Contacts domain class?

 public override void onValidate(){
    checkEmail(records);
}

 private void checkEmail(List<Contact> contacts) {
    for (Contact contact : contacts){
        if (String.isEmpty(contact.Email)) {
            contact.addError('Email is required');
        }
    }
}

Or should we prefer something like this?

public override void onValidate(){
    // delegate to fflib_SObjects class
    new Contacts(records).checkEmail();
}

[stohn777]

I'd vote for the former. I strive to have all relevant logic in the domain class with the trigger handler being essentially a pass-through to the appropriate domain.

[JazzerAcrobat]

I know I'm late to the party, but can I just check that you mean the latter, rather than the former?

• The former being "should that validation logic be a part of ContactTriggerHandler"
• The latter being "or should it be making a call to the Contacts domain class"

I'm pretty sure that the rest of your answer is that the logic should go into the Contacts domain class...

[daveespo]

Yeah, John meant 'latter' -- i.e. Trigger Handler delegates down to a validate() method on the Domain class

[JazzerAcrobat]

Thank you for clarifying!

[ImJohnMDaniel]

I concur with @stohn777 on this.

[daveespo]

I would add that adding a method like validate() to the Domain class is the preferred pattern .. and the Trigger just calls <domain>.validate() rather than having the Trigger need to know about checkEmail and any other future validations you might apply

[bdJohnson72]

Thanks for the great conversation. Glad I am doing it right.