Constraints Usage

Constraints provide Grails with a declarative DSL for defining validation rules, schema generation and CRUD generation meta data. An example of a set of constraints applied to a domain class are as follows:

class User {
    ...
    static constraints = {
        login(size:5..15, blank:false, unique:true)
        password(size:5..15, blank:false)
        email(email:true, blank:false)
        age(min:18, nullable:false)
    }
}

Refer to the user guide topic on Constraints for more information.