Domain-Driven Design in PHP

Validation

Validation is a highly important process in our Domain Model. It checks not only for the correctness of attributes, but also for that of entire objects and the composition of those objects. Different levels of validation are required in order to keep this Model in a valid state. Just because an object consists of valid attributes (on a per basis) doesn't necessarily mean the object (as a whole) is valid. And the opposite is true: valid objects don't necessarily equal valid compositions.