In Figure 3, Diagram of the TekEvent class, the organizer property is shown as a TekUser, but in our current TekEvent, it’s still a String. Now that we have a TekUser, we can fix this discrepancy. Let’s open TekDays/grails-app/domain/com/tekdays/TekEvent.groovy and change the organizer from a String to a TekUser:
We have now joined the TekEvent and TekUser classes in a one-to-one relationship. Each TekEvent instance can have exactly one TekUser. That was simple enough; however, if we save this and try to run our application, we’ll get ...