Drupal 8 Module Development

Validation summary

As we've seen, Drupal 8 applies the Symfony validation component to its very own TypedData and plugin API both for discoverability and data validation handling. In doing so, we get a low level API for applying constraints to any kind of data, ranging from simple primitive data definitions all the way to complex entities and fields. We have not covered this here, but we can also easily create our own constraints and validators if the ones provided are not enough.