HowTo: Custom Field in Lift-Record-Squeryl
Solution 1:
you are implementing your validation logic incorrectly. The correct way to validate a Record field is to override
def validations: List[ValidationFunction]
where ValidationFunction is a type alias
type ValidationFunction = ValueType => List[FieldError]
and in your case ValueType == String.
The next issue is your Domain trait. Because your call to validate is inlined into the class definition, it will be called when your field is constructed.