Drupal 8 Module Development - Second Edition

Entity validation

The last thing we are going to talk about in this chapter is entity validation and how we can make sure that field and entity data as a whole contains valid data. When I say valid, I don't mean whether it complies with the strict TypedData definition but whether, within that, it complies with certain restrictions (constraints) we impose on it. As such, most of the time, entity validation applies to content entities. However, we can also run validation on configuration entities but only insofar as to ensure that the field values are of the correct data type as described in the configuration schema. And in this respect, we are talking about TypedData definitions under the hood.

Drupal 8 uses the Symfony Validator component ...