class User {
   Long id
   Long version
   String login
   String password
   String email
   Date age
   def constraints = {
          login(length:5..15,blank:false,unique:true)
          password(length:5..15,blank:false)
          email(email:true,blank:false)
          age(min:new Date(),nullable:false)
   }
}

def user =  new User()
       // populate properties
       if(user.validate()) {
          // do something with user
       }
       else {
           user.errors.allErrors.each {
               println it
           }
       }

if(user.save()) {
           return user
       }
       else {
           user.errors.allErrors.each {
               println it
           }
       }

class UserController {
    def save = {
           def u = new User()
           u.properties = params
           if(u.save()) {
              // do something
           }
           else {
               render(view:'create',model:[user:u])
           }
    }
}

chain(action:create,model:[user:u])

<g:hasErrors bean="${user}>
         <g:renderErrors bean="${user}" as="list" />
   </g:hasErrors>

<div class="prop ${hasErrors(bean:user,field:'login', 'errors')}">
    <label for="login"><input type="text" name="login" />
</div>

.errors { border: 1px solid red }

user.login.length.tooshort=???? ??? ?? ?? ????. ? ?? ??????.

constraints = {
      title(length:5..15)
      desc(blank:false)
}