In this video course, expert Java trainer and consultant Ken Kousen shows you how to model domain classes in Grails 3 and reviews all the built-in constraints on domain properties. He walks through how to write unit tests for constraints, reviews GORM relationships that use the hasMany and belongsTo key words, and uses the Grails 3 console to explore a sample domain. From there, he examines the basic save and delete methods added to domain classes, shows how cascade deletes work, and reveals how to flush the Hibernate session. Finally, he wraps up the course by showing how to work with dynamic finders, criteria queries, and where queries.