constraints in Grails code example

Example 1: constraints in grails

class User {
    String firstName
    String lastName
    String passwordHash

    static constraints = {
        firstName blank: false, nullable: false
        lastName blank: false, nullable: false
        passwordHash blank: false, nullable: false
    }
}

Example 2: constraint in grails

class User {
    ...

    static constraints = {
        login shared: "myShared"
    }
}